Stealth heads vs Eddy performer rpm

I went to my machine shop today to drop off a rear main seal housing and a set of factory head bolts and I asked them how well the hand porting and polishing did on a set of Stealth heads they were doing for a 440 build...they showed me the bench test flow results and at .600 lift it went from 260 to 300 on the intake...I thought that was pretty good for some hand work...I will give them another try on my next stroker build...he did say that they needed to be milled .010 to flatten them out