56cc heads on a 307

Hi there. I have a mild street 307. valve relief pistons, roller rockers, Comp 206@0.50 XE250H, eddy performer intake and 600cfm performer carb, MSD box and hei. The heads are 283 74cc. I want to buy a new pair of Trick Flow 56cc. I think the CR is going to be near 9.5:1. Do you think it's going to be too much??

Thanks!

 

what kind of pump gas do you have in Argentina

 

We have regular ( 86 octanes), premium ( ~93 octanes) & ultra premium ( more than 97 octanes) gas. I want to use premiun gas, ultra premium is too expensive.