The propane pistons should give you around 9 to 1
which is a nice combo for the street and they are a standard rebuild type part. I can't imagine a "domed" piston in a 292. I have flat top Ross pistons in mine and it has just about 11 to 1. If you are going to that kind of compression you will want to add some cam or your cranking pressures will be way high and hard to start. It's a vicious circle. When you add cam the motor really wants to rev and then you have to be careful. An aftermarket harmonic damper is a VERY good investment and the use of ARP bolts to hold the flywheel or flex plate with plenty of Loctite is pretty much a must. You'll also want to shot peen the rods and use ARP bolts there as well. My 292 is in a full street '56 Chevy with a 4 speed and will run high 13's in the quarter at just under 100mph. It's fun to surprise the big V8 guys!

1964 Chevrolet C-20 Fleetside, Otis
1950 Chevy 1/2-Ton, Kirby
1950 Chevy 1/2-Ton Shortbed, Walter