Use a 7/16" diameter Grade 8 hardened steel SAE flat washer under the bolt head if the bolts thread too deep into the block. They're available on Ebay in several different thicknesses and quantities- - - -very low cost and very useful in a lot of applications. I've built a lot of small block round track race engines with them. I was using them to adjust the thread engagement on head bolts used with heads that had been angle-milled for changing the compression ratio.
Jerry


"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!