Not the cheapest....... but probably the “easiest”.

408/416 stroker with some tweaked aluminum heads.

Basically, a 4” cast crank and a set of off the shelf pistons swapped into the current motor, and better heads.

68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads