I recently came into possession of an 1989 I-roc z28. The motor is an L-98 350 with a 383 stroker kit and I was told the head has been zero decked for higher compression. My problem is it has a busted head bolt on the passenger side so I need to replace the head gaskets, would stock head gaskets work or do I need high performance ones and is thickness of the gasket an issue.

 

I would [if it was mine] take her apart and see what they used the last time.

 

If the block is zero decked the top of the piston will be flush with the top of the block. You will need a .040 head gasket for the best quench. Most stock ones will be .051 so try to get one that as close to the .040 as you can. You need that much clearance because the piston will rock in the bore as the crank reaches top dead center and then starts back down the hole. For my 377 I did the zero deck because of the stroke and the pistons used in the application. With that said I used a .039 very expensive head gasket with the intent of a little boost some day.

 

It's the block that gets "decked". The heads get shaved.
Use a micrometer and check the thickness of your present head gaskets. Thickness rating when you buy them new is based on compressed thickness (what they squish down to once the heads are torqued down).