okay, find out the type of pistons dome, dish, flat top and the volume. that will help you determine the combustion chamber you want. i am assuming you want to run pump gas, and since you want to run spray i wouldnt go higher than 11:1. i don't know to much about spray. i would say around 10:1 with 125 shot should be fine but i wouldn't take my word on that because i don;t know much about spray. i would personally call an engine builder and have them give you advice on heads. two peoplle that i am fairly impressed with as engine builders are Pete Anderson Racing and Joe Sherman Racing. I would call them up, tell them what you have and what you want. they both are going to give your different answers, but pick which you like best. give them your budget also. Pete Anderson Racing if talking to cris will probably say go with the biggest possible because he has great results with mild cam and big heads. while joe sherman might say to use AFR 185 heads.