The Clymer manual is pretty freakin great. The only thing it doesn't have is the 3 timing marks on the crank gears, counter balancer gear and crank itself. That's how you time everything. I added that into my book I have an original manual as well so I'll look through both and compare them for you

as for if it's worth it: In resale value? Not really unless you're building an all out show quality restoration and then you STILL won't get back what you put into it. Not now that you've gotta rebuild an engine. But as far as enjoyment wise: The first time that you really get to ride it you will be sooooo happy that you put the time and money into it. Trust me on this man. It's amazing. Just don't let anyone else with an lt move close to you because then you'll put even more money in your bike LMFAO

If you wanted and if it's in your budget and of that other motor is really an 87, it would be EXTREMELY worth it to take and cut away the single down tube and replace it with them upside down Y down tube to fit the 87+ center exit exhaust/power valved motor. Talk about a kiiilllleeerrrrrr pulling motor!!