Bobby,
Any decent shop should have a tester for combustion gas in the radiator. This would verify the head gasket leak. Those engines have a lot of intake gasket problems, just like the 5.7 Vortec engines. I would suggest that he take it to another shop for a second opinion. The shops that are sponsors on this forum
www.iatn.net seem to be a higher caliber than most.
There is rarely a problem with the block. If they verify a head gasket leak, the heads can come off and get sent ot the machine shop to check for cracks and get resurfaced if needed.