Trying to figure out which way to go for a 10.5 heads up class at our local track. I had a indy aluminum block but sold it and just saving money until i can find the right deal. what head would be best on a budget but still be able to make the best power for a power adder class at about 3200 lbs. The heads i am trying to decide between is the b1 original or the b1 m/c. or the 572-13 and the 600-13. I have no clue the difference in the 600-13 and the 600-13x and really didnt want to call indy. I have seen several sets of the 572, b1 original and the m/c head used already ported within my budget and i leave out the predator and pso etc because used they are still too expensive if you can even find them. I am thinking the best way is the 600-13 that uses the 4.84 bore spacing block but i need some advice from people with experience.