i think its each man to his own, some say 250 some say 300, its all up to you, but for the extrac piece of mind I would recommend going steel. Ive decided to go for forged pistons and steel h section rods, the zvh block is costing me 1300 to be built with new block, new (standard) crank, pumps and heavy dudty bearings. the engine is rated at over 450bhp so should be pretty reliable (but it is a ford.lol)