I built a 383 for my 69 C10 a few years ago and recently put it on the chassis dyno. It made right at 400 hp to the tires, same for tq. HP peak was 6,000 rpm. Dyno operator said it was 500 at the crank all day long. I would recommend going 383 as the extra cubes do help and it's about the same cost as building a 350.
Profiler 195 CC runner 64cc combustion chamber as cast aluminum heads
https://www.profilerperformance.com/...y-racing-heads
Howards Rattler Hydraulic Roller
https://www.howardscams.com/hydrauli...cams-118045-09 killer sound
comp cams ultra pro magnum roller rockers 1.6 ratio
eagle rotating assembly, 10.5:1 static compression
edelbrock performer EPS intake
custom built holley 750 street hp
DUI ignition HEI
1 3/4 primary full length header, 3" exhaust