A roller LA to low buck a build? IF! You stay with the roller cam, be careful on the cam you choose! Watch the riming events!
Without touching the heads? Mild lift cam to .500, duration to suite the rpm band you want to operate in.
(Don’t get greedy here!)
1-5/8 headers I like to avoid in favor of 1-3/4, your call.
Dual plane intake, your choice carb & air cleaner, multi spark ignition, now your down to gear and maybe a stall converter depending on the cam.