Sounds like you are building a sb chevy motor. The vortech head chamber is not all that good, I have a set on the shelf and there is very little differance in them and some old 1970s heads, ports are shaped a little better but thats about it, the chamber has nothing to do with them being a better head than the old ones. They can not handle compression as well as a mopar magnum head.

I see a lot of combos lister here with high compression that "run fine on pump gas" but they are retarding the timing to make up for it, as a matter of fact most of the combos listed on this thread are doing that. That just demonstrates the need for tight quench and no .065 is doing nothing for quench. Over .040 and .050 max you gain nothing from quench. Most big block mopars with there horrible chambers and spark plugs on the edge of the chamber like at least 40-42 degrees timing for max power. Small block mopars can get away with a tiny bit less timnig because of the much better plug location, now a magnum head and tight quench and you can find peak power at 32-35 degrees and run higher dynamic compression.

If you still think a Vortech chamber is real good set it next to a magnum head and you will wonder why they put a stone age chamber is in a head desighned in 1995.