Big Block or Small Block in my 70 Duster

will the moroso valve covers clear the booster too or do I need to run manual brakes? reading alot about handling. Seems to be a good consensus to run 340 torsion bars with SS springs.............planning on tying the subframe together as well. What are everyone's thoughts on the 1.03" torsion bars? Do they make the ride too stiff?

Kinda leaning towards a small block for now - just because I got all the pieces parts already! Just need to figure out what to build. 340 or 360? LOL!