Yes, they will fit. Your machinist should know exactly what to do. First, they replace the valve guides so that the seat and bowl cutters will have a proper concentric alignment. Then they hog out the bowl area (valve pocket) under the valve with a big cutter as there is little sense to use bigger valves with the same old size just under the valve. Then they establish the new seat with a light cut. Additional cuts are made to form a multi-angle on each side of the seat cut for better flow. At this point the machinist should stop and return them to you, as the bowl cutter will leave small steps or angles that need blending into the remainder of the bowl (port roof) and the port floor radius.

Once that (and any other work accessed through the valve pocket) is finished, the machinist makes the final seat cut, usually with a 1° interference for better sealing and additional angle cuts if not done previously. The reason the final cuts are done last, it that a tiny slip when blending can nick the seat, ruining the valve job and requiring more cutting to repair, sinking the valve lower and stealing some of that new flow capability. Hope that helps.

David

EDIT: BTW - if you're spending the time and money, why not just use C9, D0 or GT heads? Less work for the same or better results.