Anyone Know of Online Engine Dyno Software so I Can Test a Few Combos?

How much compression can you get with just a piston change (on ~65cc Edelbrock heads)? Don't necessarily want to have to deck the block if I don't have to since I'd rather not have the car out of commission very long.

Your stock pistons have a compression height of 1.741"
IIRC. KB167 flat tops are 1.810"... that's quite a difference. stock flat top 8.6 to 1, The KB's around 10 to 1...