Heads are coming off, complete disassembly and cleaning, source and install new valves and lap to the seats (grinding seats may be necessary...), new seals, reassemble and re-install with new gaskets: If you have a shop do it you're probably looking at $1500 or more. Unless you have bux invested in port work on the heads or they are aftermarket already, you're probably better off simply
replacing the heads and using the old ones as cores or selling them on ebay to recoup some costs.
Q: Why do you need to replace the intake valves? PTV?