What's a good after market manifold to run on a 30 over flat top piston engine for good all around power,going to use large ovel port,some say the small ovel port's make a lot of torque???any ideas. Thanks JOHN SR

You basically have 3 types of factory BBC heads, peanut ports are small and came on the bace model 454's. Large ovals are very good for what you are doing, they are bigger than the peanuts but smaller than the rectangular heads. The rectangular ports have larger intake runners and came stock on all the 454 and 502 Mag engines, they also work well on 540's.
If you are planning on keeping the engine a 454 I would use the large ovals. I have a 489 stroker engine and I use the 820's. If you are planning on building a 540 or bigger in the future then the rectangulars would be a better choice.
What do you have now?

I run a 781 head which is a large ovalport head built in late 70's, but you said manifold (intake manifold ?) With your build maybe a performer air gap.
You can put domed forged pistons in your motor to up the compression if you are doing a rebuild..

I agree with the Edelbrock Performer RPM Air Gap.

I used a Weiand Stealth on my 427 in my 242. I like the stealth over the RPM due to divider is cut all the way to the plentum floor. My engine spins to 6000 so that helps upper power. If your not spinning that hard the notched rpm is a great choice as well.

beg to differ.....after all ive read an tryed,....edelbrock air gap the BEST