Almost O/T - Do the 250 engine side mounts work on the 292 (I know you have to reposition the frame mount)? On earlier trucks the frame side steel was different, but IIRC on the 73-87 the parts are the same, just need to be shifted to the correct location. Wondering because I'm looking to d a swap similar to yours if I find the 292 at the right price.
From what I see the left side is OK but the right side moves. But the frame rails on my 79 truck will handle that it looks like. If anything maybe drill some new mounting holes in the frame rail.