The $325 to mill a pair of sb Mopar heads .040 does seem sort of high...... unless it also includes milling the intake side the corresponding amount.
Of course, if you bring in two assembled and/or greasy, oily heads........ some cleaning has to be done prior to putting them in the machine....... maybe that’s part of the price.
If you brought me two disassembled heads that were pretty grease and oil free, the milling of the decks(only) .040 at my shop would be $120.
Mill intake side, another $120.
In most modern machines, the head sits upside down, and milling .040 off an iron head makes a lot of filings........ that cling really well to anything even remotely oily.
If you brought me two assembled oily heads, wanted the decks and intake faced .040....... and the wanted to receive two assembled heads back...... it would easily be $325(probably more).
Just depends on exactly what you’re getting for $325.
If that the price is for milling the decks only, nothing else...... that seems like the “I don’t want your business” price.