ive never reaport bothered with raising the exhaust. always felt better widening them.
though some raising is necessary to develop the required radius...DONT grind the top (or bottom) of the port square! make it oval shape, far gentler on the rings.
its an idea to get both transfer ports cleaned (theres always a lot of casting flash left in there) and MATCHED, so they open at exactly the same time. requires some delicate handling to get a good result. also an idea to round the tops of a bit too.getting in there with standard tools is a nightmare...i got dentist drills specifically for doing such things... but a 6mm(or 1/4") endmill will fit in a die grinder and will "just" clean up the flash.
chamfer the edges of the ports slightly. once again...gentler on the rings.
also, match the transfers to the crankcase, theres a good 3mm overlap in most engines down there. overlap is bad news