It will be easy to check if the seat are hardened or not when the shop does the valve job , if they are hard the guy doing it will know . I had a set of 452's taken out to 1.81 on the exh and they didn't need to have hard seat inserts installed .

If the heads have had a few VJ's done the valve maybe be recessed , only way to fix it is hard seats or install larger valves.

I trust the guy installing the seats in my heads that he is doing them right.