Good point. I'll likely sandblast the body or glass bead more than likely. As far as the generator/welder portion most likely good ol' fashion elbow grease with a wire wheel as suggested. The engine however will get carried over to the Cat dealer I used to work at for a good ol' fashion acid dip along with the head. I've tossed engine blocks out of D11's in that tank straight out of the coal mine and after a couple days they are ready to paint.
I'm working on finding out the numbers on my second engine and will most likely be calling on you for some prices, gaskets, main/rod bearings, carb kit and so on. Also need to know the standard bore on one of these old things so I can check it out and see if I can get by with a simple hard hone and rings or if I'll have to take it 20 over. Hopefully can just hone and ring it to keep costs down. It appears that my chief mechanic(me) is wanting to do a complete overhaul, I suggested just fixing the leaks and getting it running, but he ain't going for it!! :-) Tells me do it now and you won't have to touch it again in my lifetime.
So, once I get the engine done, get the chassis all cleaned up then all I have left is the generator portion. Hopefully some brushes and some new cables(they look to be about 50+ years old) and it'll go on. If that don't do it, well, what's a few more dollars. I hope to keep the whole deal around $2000, then I'll only have $2300 into the old girl, still cheaper than what I can get a used one for and then I'll know every bolt, gasket and part on the machine.