Post a picture if you're actually concerned but from the sounds of it im sure its completely fine. cracking in the head is a much bigger issue than that.The shields form a mating surface anyways so just so long as the injector boss can take the injector at full torque i see no problem. then again i may be misunderstanding what is in question. please post a picture
Post a pic to be sure we're all on the same page.
I do know that I drive torque, while listening to my friends prattle on about horsepower.
Can you clarify that the ridge that looks like the moon's crators where the heatshield rests on is not just greasy gluey crud; and is actually seriously depleated aluminium?'Cus if it is, then unless you handed this 'fellow' a body shell in equally bad condition, then he has given you something not really fit for purpose
take that baby to a welder to get the aluminium built up and then to a machinist to get them milled to spec. I've had a race head fixed by the weld and machine combo. It took a tonne of abuse before the crank let go. Its on my dad's car right now, still working. You need to make sure the welder knows how to weld that though. It needs a preheat and post heat so the metal doesn't become brittle and break.