Find a reputable builder, it took me 15 years and about $5k in metrology gear to learn the difference between shiny and good. I've learned that there are a lot more shops out there that are run by mechanics than there are run by machinists. Example, Few understand the merit of valve seat to guide Concentricity, and fewer still understand how to measure it properly, and why the fowler gage is a POS. 609 does. I discussed a lot with him on PB about 4 years ago when I tooled up to do head work on my mill, but then had my son and my priorities changed. There are 3 people I'd let do machine work for me....609 is one of them...but he's not tooled to rechrome wacker cylinders :-)