The ZZ3 is an over the counter later than 1986 Chevrolet crate engine. Uses a special one piece oil pan gasket. Its a 5.7 liters = 350 cubes, 4 bolt mains, pink rods, low rise aluminum intake, Hei distributor, also has the good corvette HO aluminum heads. Hypertuperic ? pistons. Valves are 2.0 on intake and 1.55 exhaust.
Its a factory roller cam and lifter engine. Put the GM HOT CAM kit in it with 1.6 roller rockers, titanium locks, special valve springs with hardened shims 218 intake and 228 exhaust , gives you 525 lift and that motor really comes alive too 420 HP and 400 foot pounds of torque. Problem is cam produces low vacuum of 14-15 " and will need a vacuum pump to operate the brakes to get the 18--21" vacuum necessary .
Throw a pair of those new chevy fast burn heads on and pick up another 30-35 HP
mike