New guides on a 964 then what?

[Porshaah]

Hi all

If I replace the valves and guides myself with new ones using the procedure of drilling the old guides to reduce the wall thickness (i.e. what drill bit size or wall thickness should remain) and cooling the heads in a domestic freezer then pressing or knocking them out with a drift? Would I still require having the seats machined if they are currently in good condition or can they just be lapped in? To drill them out is it recommended to drill them out with a hand drill free hand with the old valve guide hole as a guide for the drill or should I set them up in a drill press at the proper angle (i.e. again using the valve guide hole as my reference angle) and clamped to the table? Is there any machining required on the new valve guide before (i.e. to the correct interference diameter to ensure good clamping) after (i.e. machining - hone ore ream inside valve guide hole diameter) installing them? I remeber visiting a well known website a year or 2 ago which listed prices for certain jobs (i.e. valve / guide replacing and the accompaning machine work required) but can't remember who it was - does anyone know?

Your responses are appreciated
Bill