AS for the oven brazing i'm not sure there is anyplace here in the middle Tennessee area that does that. IIRC it was very expensive to have done even 25 years ago.
At this point i'm not sure if it can just be welded due to precision sealing surface at bottom of sleeves. Complete disassembly and reassembly of the engine is not a problem as long as i get the cracked fixed.
THe Service Manual (factory) and others i have talked to say that cracking at the block webs is fairly common. I'm wondering what causes it.
As for an engine swap to the 4cyl Chev or Ford engines recommended by others i'm wondering if an adapter plate is needed and who sells them.
I'm not too worried about a lack of governor. I have a real nice TO 20 i use for applications where governor is needed. But this TE 20 i plan to use as a spare tractor just for towing things around the ranch here so i can live without a governor on this TE 20.
Altho i do prefer to keep the original engine, rite now i'm looking for the fastest cheapest and easiest way out to get this tractor back in service.