My home inspection of Speedmaster heads

rednesss said
So, if you wanted to have a better valve job done on these heads, would the machine shop have to put in all new valve seats, or could you cut a 3 or 5 angle valve job using the existing seats and then also re-use the existing valves?

They should be able to tune up what is there. The 45° seat could be narrowed a bit and a couple angles below and above it to improve things. Then blend into the bowl to smooth things out.