Fitting larger valves to a cylinder head is, if the desired larger valve is the correct-length, with the same stem-diameter, and valve spring installed-height is the same as the originals, a slam-dunk to accomplish. Porting a slant six head is a time-consuming, expensive process, fraught with the possibility of hitting water, something that is not easy to repair.
I have heard prices that range upwards of $1,500.00 for a ported head, complete. Simply putting the oversize valves in, doing some "pocket-porting" in the valve bowl area and letting a couple of more pounds of boost make up for the flow restrictions of the un-ported casting could save upwards of $1,000.00 if porting is not utilized in the "build."
Unless the engine is to be a balls-to-the-wall, all-out, NHRA Competition Eliminator effort where every HP counts, it seems to me that it makes $$$$ sense to allow the turbo to make up the slack by adding some extra boost in lieu of spending another grand on porting.
Just my 2-cents... :happy7:
