P2V is based on your cam lift, timing, piston reliefs, valve angle and diameter, rocker ratio, deck height and gasket compressed thickness. I can't help you with all that without a great deal more info, but the TWs have fewer clearance issues than straight-valve heads for the same combinations. That is a builder's job to figure all that out. Likewise, the gasket compressed thickness is based on deck height and desired quench clearance. Using the actual measured rod center-to-center length, piston compression height and measured stroke, the block would normally be machined to achieve the desired deck height. That is then coupled with the correct gasket to produce the desired quench clearance. The desired quench is variable depending on factors such as bearing clearances, heat expansion, maximum RPM and resulting rod stretch, rod material, etc. For a typical street engine on pump gas with typical parts, .040" is a good target. Machined for a measured zero deck height and with a typical .039 to .041 performance head gasket - you're generally good.
David
