ok, race gas does not come in any premix. it is a more pure less combustible form of regular gas. RG comes in various levels of octane. much like what you see at the pump, but instead of seeing number slik 87, 89, 91, 93, youll see 101 100 110 105 and higher. these higher numbers resist predetonations (this is what caused the little marks on the tops of your pistons) from running too high of a compression ratio in your motor. so when i said mix with VP Red i meant take 2.5 gallons of 91 octane reguler, umixed fuel, and put it in a can. Then put 2.5 gallons of Red in the same can and shake it up. the two fuels will mix together and the octane ratings (91 and 105) should average to 98.
**AFTER you have mixed them then ADD your premix oil.**
VP red is a 105 octane fuel made my Vp fuels and is reasonable at 4-5 per gallon.
However if you do get your coolhead you may not need this because, depending on which domes you choose, your compression could be lower.
As for a head, i have a Pro Design head and i like it. Some like the Noss head, other like the RK tek. The PD and the noss are 265, while the RK is like 350.