OK, here is a a crazy *** idea, it might work, and it might not
The international v-537/605 engine has a 4.625 std piston with a 1.313 in pin. (???) If I have read that correctly, at my age that is always questionable, is it possible to use this piston in the 351/702. What I don't know is the compression height. If it is within a few thousands the top of the piston can be reduced. The piston can be re-bushed to fit 1.25 GMC.
OK, let's shake the bushes and see who had gone this route and found a dead end.
Edit time , aw rats, compression distance-2.31"
wrist pin-1.31
approximately .5" from the surface to the top ring and .200 dome
3 rings
Maybe a little long rod ???!!!