Numbering and arrows ought to be all one needs then. As for align boring the caps and trunions, the machining would cost more than another head that had no problems. That''s why I didn't even really consider it. Thanks for the reply on markings. I just found one of my loose heads (ZX rather than ZG but the same) in the shop yesterday so I could have looked for myself. LOLqman said:They are numbered left to right with an arrow indicating the front (driving direction). There is also the possibility to re align bore the housings if your machine shop is equiped to do so. It does lower the cams slightly in relation to the head gasket surface, which will affect cam timing "slightly". But it's not any more that if you had any other cylinder head machined for warpage. The camshaft adjuster will look after the slight amount of slack created by this as well. If you've got enough money you can do just about anything!