Something to consider: Go ahead and ship the Series 1 over to England and have it worked on there. Seems like there is a lot of knowledge and parts available readily in the UK. You could also see what you can do about getting a few more HP out of that engine which would be grand. That said, if you build it near your home, you can do a few shake down trips. This familiarizes you and your family with the gear, vehicle, and you can start working out bugs. Having a problem within AAA range of the house is better than in BFE another country.
Also engage others in the trip planning. I just got done with a trip and I planned EVERYTHING. In all honesty, I didn't have fun because I was too busy making the next thing on the plan happen.
Spares, I'd bring a spare water pump, hoses, fuel pump, carb rebuild kit, spark plugs, coil, distributor cap and button. Swap over to a Petronix ignition (get a good Bosch coil to go with it, the flamethrower coils have a bad reputation) and then you won't have to worry about points and crap. Those are the only major items that I can think of that could crap out on you and leave you stranded. Which is a bad time.
Even if you pop a coil after 4 weeks, you can replace it and then you figure you've got 4 weeks to find a replacement. Such is life. I know the fuel pump is a problem with my series 3 so spares are always crucial for me. It is what it is.
Search here on this website. Some guy got his family crammed into a Jeep Wrangler TJ (the Jeep before all this "4 door" nonsense). He has A LOT of suggestions on pairing down crap. Its amazing what you can get away with weight wise. Their family had to rough it a bit more which they were cool with. All part of the experience and all that crap.
Parabolic springs. Get them. Oh and new seats. Your body will thank you.
Look into sound proofing. Lizard skin comes to mind. In my Series 3, sound and heat are big issues that add a lot in terms of fatigue. Also buy everyone in your family noise canceling earphones. That way they can drown out the noise of the crappy old truck and have some alone time listening to their preferred music. Podcasts also bring multiple kinds of win.
Steering damper. Yes. And renew the steering all together. When the steering gets about a 1/4 turn of play in it, you start complaining...a lot.
Look at carb upgrades. Long story short, seems like british carbs are goofy and make no sense. However a nice Weber that you can easily swap out the jets when you start climbing in altitude will make a difference.
Buy this:
http://www.safetyseal.com/
Let me explain to you the awesome of this kit. IT IS AWESOME. First off, its easy to use. Have fun fumbling with any other kit. This is super easy to use. On top of that, it works fantastically. As I can only imagine, crap in the roads will be prevalent. Also with this, you can get rid of tubes. You just replace and go. Also a good 12V air compressor is worth it. Don't skimp out here. Also with this setup, you really only need 1 spare, saving you space and weight.
One of two things: Either install about 4 12v plugs for all of your family electronics, or minimize your electronics. That is always a huge problem with me. I have so many electronics that all of a sudden, I need like, 5 USB ports to charge all my crap... and that is just me. This is a personal flaw but I don't want you to get caught up in that mess. On that note, a nice bluetooth sound bar is awesome at camp. Especially one that takes the same charger as your phone.
On that note, LED headlights. Let me explain to you the missing link in your life. You are incomplete without these. Holy crap. So much epic awesome. Like, I don't need aux lighting with these puppies. Well I keep my 20" LED light bar, but that is because its my toy and I love my toys.
Seriously. Peterson 701c LED headlights. Doesn't draw any extra power so you can keep your stock wiring and they put out A LOT of power. On that note, look at replacing all the bulbs in your series with LEDs. Less power usage and they work better.
Replace alternator and look at getting a mean green starter or something heavy duty like that. In the cold, that is when these guys shine. Instead of being in 9F and nothing works, these guys will help get you turned over. Then your engine gets a bit of heat, next thing you know, choke is half way pushed in. Great success.
If you are putting in new glass, get said glass tinted at the same time. This will make a HUGE difference with direct sun as well as night driving. Helps with the glare from the lights from the back of the vehicle. I'd say that is a huge problem with my 109. Headlights of modern cars just pierce through the cab. Its very annoying. I try not to drive at night in my 109 but sometimes it happens. Actually this is the main reason I don't like driving at night. I have a feeling with 12,000 miles ahead of you, you'll end up driving at night.
Check into aftermarket radiators. My series 3 came with a 3 core radiator. Upgraded to a 4 core. Up until this year, typically it gets into the 3 digits here in Georgia. No issues with the truck running hot when it was 107 at 4pm with the sun beating down. Now I crapped out but the truck didn't.
Buy books on the places you are about to go. On a recent trip to Colorado, it was cool driving from Silverton to Ouray and my dad reading about the history of the piece of pavement we were on. Helps pass the time.
Get a funnel with a strainer in it for pumping gas. Easier than having crap in your tank.
That is all I can think of. I'm a series 3 owner, not a series 1 so some of this information might not be applicable, but hopefully close enough.
