323 355 or 373 gears??

OK gotcha- so you think Ford 9” or 8 3/4, or do you think my 7 1/4 will handle the 465 HP?’

If I did a Ford 9” or 8 3/4, what would make the it cheaper on install?

One of my concern is I want to keep stock gas tank, I read some forums 60 fits with stock tank in 67’ Cuda, but looks tight to me haha.