If going with less than 500bhp, std mahle are well up to the job, and have stacks of meat for valve cut outs, the person I use charges around £35-£40 to do all the cutouts, NOT per piston, I used mahle myself, as just about done mine myself(nearly finished, other things to do).
My engine had done 200,973 miles on std bore, and even after this mileage it only needed a polish on the crank big ends and mains so still std size!!
tabetha