A fellow bus-nut in central Florida has a running engine taken from a 4106 and he could ship it. If you want more info, call him direct. His name is Leonard and his phone number is four-oh-seven, four six six, four five eight seven.
I'm sure you know this already but I'll say it anyway: the risk of doing a rebuild on your existing engine is project creep. That's where you go in at $X,XXX and come out at 2 or 3 times $X,XXX. Its not that the shop is crooked or gaming you - it just happens. The advantage of any crate engine, new or used, is that the acquisition cost is a known amount - all you have left to deal with is removal and replacement.
I gave him some info on a good engine that has VS transmission it's in a AMC General what does it take to install from a AMC to 4106 anyone know for sure I don't