Are the port size standard or bigger for Mace's replacement aluminium ecotec/l67 intake manifold gasket? Can I get a measurement on that, I will get a set if they are bigger, to suit ported heads.

They're similar to the factory gasket port sizes. The mean port size of our replacement aluminium ecotec/l67 intake manifold gasket (GSK601) is 25.6mm X 51.4mm. Please note that even if the port size is smaller, these gaskets can still be ported out.