I generally don't check this topic which is why I'm a bit late here but the Taipan Gold Head doesn't have an option for side exhaust even though it can be assembled that way. The ports only align as rear exhaust.
Maybe you are right. I just looked and it looks like the previous owner milled a new port under what would be the exhaust on the rear, and modified the front one to match the side bypass port. It goes pretty good that waythough. I haven't checked as a rear exh. because it may wear differently. Do you know how the MVVS .15 is supposed to go? The ports match up for a rear exh. but it came with a side exh. muffler. It runs the same rpm either way, even with a fairly bad mismatch.