Good to see you found an M1010! I'm glad to see more M1010 stuff since I've had to park mine for the last 8 months
. I'm sure you have some fun plans for it though! When I first bought mine and drove it home I made a detour through Moab and I was amazed how well it did off road stock. Then sad to see the fuel economy drop from 15-17 mpg to 10-12 mpg when I put 37's on. I don't know why everyone gets upset about the cruising 55-60 mph. It gives you the most optimal fuel economy, plus anywhere that is worth seeing you can't drive over 55 anyways. It kind of stinks on the interstates, but I get pass all the time and then catch up to the same people five minutes later fueling up.
If I were to build my truck over again I would have done a few things differently. Mostly just some of the things I wish I would have prioritized first.
First and foremost I would do the banks turbo or 6.5l turbo first (if your planning to do a turbo). If it was me starting from scratch I would absolutely make this first priority. The only time I've ever felt like the truck is under powered, even with 37's, is going up a mountain passes over five thousand feet at 30 mph with the semi's. All the rest of the time I'm happy being naturally aspirated, but it drives me nuts not being able to maintain 45-55 mph then. The poor old diesel just can't breath enough.
I'm not sure on your plans if your going to do any drive train mods', but I wish I would have made my box more camper friendly before I dove in and did tons of mechanical modifications.
You can also stuff some decent sized tires in these trucks by just cutting out fender wells if your going that route. The box is easy to do and the front fenders were more of a pain but not impossible with some fender flares to cover them. You will probably have to cut the fender wells even if you did a lift kit. I just wouldn't make that the priority...
Should be a fun project! I spent a total of about 3 months living/traveling in my M1010 in 2015 with my at the time fiance. Now were married now so its safe to say gals love them too!. A few of the camping creature comforts helped. My wife had some good ideas about simplifying some of the storage. Since we kept the aluminum structure mostly stock (I don't know if your gutting yours or keeping it original) in the back of the box for the bottom storage. One thing I am going to change is to get rid of the sliding covers setup. It seemed nice to have all that storage right there but what we found is that all the random stuff would bounce around and make it tough to get at anything you wanted. So My plan is to take the cut off disk and remove the bottom lip so it is even with the floor then build some pull out drawers that fit in there. All that nice storage just gets too cluttered. Sorry to rant...
Have fun!