Bare Bones Budget 400 Build

I never heard of a 3 spd being standard behind a big block, just 4 spd’s. The small block and /6, yes!
3spds were actually standard on 340 Dusters/Darts and Road Runner/Super Bee after 1969 (IE:1970) as a way to keep the base price of 340 and 383 models under $3000 (B-body) and I think $2700 (A-body) like 1968/9 with 4spds.