i blew a head gasket on my 91 camaro 305 tbi.i took the heads to the machine shop for vavle job and resurfacing.he took them down .020.will this affect anything with the way the computer runs the engine?and will it boost the compression enough to tell it? I've never had much dealings with newer computer controled engines so any help would be appreciated.

thanks in advance

 

If you have stock pistons then no. It is not even enough to worry about higher octane fuel.

 

Chances are you're going from a stock .015" thick head gasket to an aftermarket .039" thick one, so that .020" milled off will make it pretty much identical to the way it was before.