i checked mine by putting the head on the block with a hea gasket but no bolts and it hit with at least 1/8 inch gap between the head and block when the piston was at the top.a head spacer will help.
Also I NEED some verification whether i will need to make valve reliefs in the early obd1 ABA pistons?
i would search this site and find out what people did and then find a machine shop that will do it.im no expert but if the intake valves open when the piston hits tdc there done.heads done.the 16v pistons are recessed for a reason.it shouldnt cost much to get done.you just need to figure out what to do.
I ran OBD2 ABA pistons in mine for a while, and decided I wanted a higher CR, so I swapped them for stock 9a pistons.
I had contact marks on the pistons from the valves. Didn't bend any, but definitly hit. I think the head had been shaved prior to my getting it, so that may have played into it. I bolted it together with some clay on the pistons, then spun the crank. It looked like it was going to work, but must have gotten closer as it heated up.
Long story short, it may be well worth the time to cut valve reliefs in the ABA pistons (~8.5:1 CR) or use 9a pistons (~9.2:1 CR).