70 duster project

Skip the cut outs, they’re almost always a power looser unless you scientifically figure it out on a dyno. You would be a world ahead of you follow David Vizards exhaust example recommendations for sure!

That would be a header extention into a pressure wave cancellation box, each box being at least 360 cubic inches necking down to the exhaust pipe into the mufflers.
Big difference!

A lot about making horse power is now well the cylinder heads flow in AND out. This would be why the Trick Rlow heads gets the nod by many here since it’s a very good high flowing head that is t a bank breaker. A bit more pricey than an Edelbrock head, BUT! It’s already CNC ported and it will make the most power with what ever cam you use.

Speaking of a camshaft…. I’d have one on a LSA at 108 in that 340. A cam at 230@050 (give or take a few degrees) would be pretty good with the 3.55’s.
Use as much lift as you can get to take advantage of the cylinder heads air flow capability.

With a stick shift car, I myself would run a mechanical cam. Look at Hughes engines for starters. Also Howard’s cams and Schneider cams. Remember it’s only a few bucks more to have one custom ground with melts away as time and usage go on.