Welcome to the board!! That motor's carburated now,right? As said,it's a bolt-in.That 3spd ain't the strongest in the bunch.It depends on it's condition and how you drive it,too,of course.Last time i checked people don't build 400 horse motors to go easy

.A car 4spd will swap right in,like Muncy M20/21/22,Borg Warners,and Saginaws.The list starts off the most expensive and works down a bit in price.