The 250 Chevy and the 350 Chevy engines use the exact same motor mounts, and there are lots of places selling motor mount kits to put a 350 in a 47-54 Chevy Pu. Hope this helps. Garry K

Garry K in Pac Nor West
1948 Chevy PU 235 SM420 4 spd
1932 **** B pu
1964 Datsun 4x4 with SBC, SM465 4spd and Rockwell xfer Dana 44Fr and 12 Bolt Rr.