you have to look at the power level your chasing. acl may be good value, but will they take 700hp worth of punishment? doubt it. ive used acl pistons before, and dont get me wrong, theyr great. but you have to do a complete package, not just pick and choose parts, as one part may be a weak link in the chain, and fail destroying your motor.
and dont go second hand, many drag motors have pull downs every few 100kms, but they do get punished in that period, and may be ready to fail.