I talk with sussex engine rebuilt shop here in New-Brunswick and he told me to take the loose of the pushrods and then 1/2 turn. He also have a dyno for 300$ for half a day or 500$ for a full day if someting goes wrong. That's include breaking the cam, set the carb and the timing with exhaust sensor on 8 pipe of headers. He have a few boat in the parking and a engine in the shop, 502 stroke with a blower that make 800 hp and show me the dyno result because i never saw that and i was curious. He also shoe me 4v head from a 351c with bad timing and the valve was hiting all the pistons until 1 piston broke and ruin the close chamber head but the chamber was larger than my australian heads, might be cobrajet head 72-74cc if my memory is good. He said i should go bigger with my cam since i have xe-256h. I just receive my costum lenght pushrods 9.300 intake and 9.400 exhaust from him, very nice guy. The passenger head is done i'm very happy with the result. Can't talk any more the driver side need pushrod/rocker setting. Can't wait to braeking in with dyno result.