A buddy of mine did a swap like yours 10 years back or so. Dropped a 350 in where a 235 used to be.......on a '62 C-30, SM-420 4 spd.
He used Ram's horn manifolds for the exhaust; which had the mounting for the Alternator (the 235 had a generator).
Motor mount was center, front. So, went to P-n-P and found a "horse-shoe" mount from another '62 Chevy truck. This bolts to the front mount bosses on a SBC and bolts down to the crossmember.......no mods, no drilling required.
The '63 and up models have the coil spring suspension and a different crossmember.........which uses side motor mounts and is drilled for either a six or a V-8.
I know, I had one.....'63 C10.........283, 4 spd.
Does this help?
