Yeah the 10.0:1 is those pistons at the 9.240 height, so the longer rod and my shorter block I would be above a 10.0 ratio.
Stock ratio is 9.4:1 for the LQ4 and 10.0:1 for the LQ9. The LM7 is a 9.5:1 stock. Some guys have 11:1 and run around 8psi pump or 15ish on e85 and are OK. Its all in the tune. the lower the CR the more boost you can run and the more lax the tune can be… usually.
They are 71cc heads also. so with the rated CR on the Wiesco site @ 9.240 height it would be a hair less than 10.0:1.
the next choice piston is the -11CC pistons at a 9.2:1 rated (actually a bit lower with my block) and even lower than that with the shorter rods. BUT in theory I could boost the balls off it. But thats loosing a bit of off boost tq and putting more strain on the heads/bolts/gasket.
I think the happy medium is the 10:1 or so, and about 20psi. Still “high” boost some say for these motors but enough compression still there to make good power.