i think you have to find out what your comp. is, what your bore is, and what your elevation is. then when you talk to whoever about the head tell em what all that is and they should be able to help you out finding the right domes and then your jets if you have to rejet. ive been trying to pull the extra cash together for new rings and a noss head with 20 or 21cc domes. my elevation is 530.
good luck to ya man :beer: