What cam are you running?
The exhaust side is where the help is needed bud. Look at the ports.
Exhaust valves and ports need only be 3/4 of intake size. It is much easier to empty a chamber by pushing out than it is to fill it by sucking in through a carb and a manifold.
Even though this is my first slant engine, I am a big believer in porting. When you think about it, people pay big bucks to get a valve only .14 larger when they switch from 1.88 to 2.02 valves. 1.88s are smog dog heads and 2.02s are performance heads. Yet the difference is only .14. Now look at the bowls under your valves on a stock Mopar; completely choked up. You can open them up .25 or more. Frankly, I would take a properly ported 1.88 head over an unported stock 2.02 head any day, and have in the past.
Then look at the lousy port shapes and surfaces in the stock heads, especially back in the 60s and 70s. Its like no two are the same. One of the reasons modern engines blow away older engines is not just fuel injection and turbo charging. The quality of machine work and the shapes of the runners are far superior.
Compare a new aftermarket SB head with an old stock one. No contest. The difference is in the ports.
I would never build a performance engine without porting the heads.
