360 J head Valves
What size valves do you have now and what size are you loooking for? The largest that will fit are 2.02 intake and 1.60 exhaust. If the seats are sunk there's no other option other than replacing them. If your valves that you have now are the smaller 1.88/1.50 sizes and he replaces them with larger 2.02/1.60 sizes make sure he uses a cutter to remove the excess shrouding from underneath the seat or you really won't gain any flow to speak of.
BTW: When you get those 2.02/1.60 valves in there they nearly touch. Not much room between them. Nothing to worry about though. Some factory heads had them.
If your looking to buy valves Mancini racing has pretty good prices on them when you buy a full set.
www.manciniracing.com