Replaced the 305 in my 87 iroc z with the GM 350 HO 330 and got 280000 miles before it hydrolocked. Anti freeze came out of each plug hole when pulled. Not sure YET why. More will be revealed. Thought about a new same long block but putting a z4 cam, 1.6 rollers... if I rebuild what would you do to get more HP?

 

The ZZ4 cam won't gain you much. The 1.6:1 rockers by themselves would be a small gain. Skip both of those and order a new Lunati 54743LUN cam. That'll add at least 30 HP, maybe more. If you want roller rockers with it, use 1.5:1 intake and 1.6:1 exhaust. That'll add another 15 HP. Top with an RPM AirGap Vortec, it'll be a good gain over the intake manifold that came with the 350/330. At least 10 HP, probably more.