Hi TeriAnn, I was wondering when you were going to chime in.
I've recently moved to a place where the only internet connection faster than 1200KB is satellite. I'm signed up for it but until it's set up I go to the local Mall food garden for an internet connection. Mostly I've ignored this forum during this time to get other things done whilst online.
Don't forget the engine that burns brighter burns for a shorter time. 200tdi cylinder heads are NLA. Some folks are installing a 200tdi without the turbo (200di) for vastly increased service life. The power is very close to that of a 2.5L petrol.
Since you want to install a slush box why not go with the 300tdi? More parts are available for that engine and it mates to the LR coiler slush boxes found in US wrecking yards. Or better yet the newish IH 3.3tdi?
Putting a slush box into a Series rig will take some effort so most any powerplant that fits shouldn't add a whole lot more work to the project.
If you intend to pay Timm to do the installation, go with the diesel conversion he is currently in favour of. It's been my experience that he does better work on a conversion he is currently in favour about. He has a lot of real life experience so anything he recommends will probably work for you.
Just remember an engine that was offered for sale in California on a vehicle that does not require periodic emissions is the engine you want. Assuming you want to have the vehicle legally registered, don't want to go through emissions testing and are open with your insurance company so they don't have an excuse for not paying if worse comes to worse.
Good luck