and if the original seats are serviced-out just use a valve head diameter slightly larger to edge out into new material and start over. FWIW i've heard doing seats in Cleveland heads is not text book and no walk in the park. special shallow seats are required and knowing how deep you can cut is critical.
check out Bill Diehl's comments in this thread,
especially " a lot of research was done to see what kind of seats would work, there is water under there
Exhaust 1750-1450-325 they where custom made be CHE, an off the shelf 1750-1370-375 would need to be cut down "