thanks for the input Jack and 2M. was out all evening... scored a couple vintage Suzuki and chrome Hodaka gas tanks in nice shape for latest builds from local bike salvage yard.
current motor work is an '83 GR650. will post a couple pics soon in another thread i started a while back. did a fair amount of porting, and both intake guides were cracked so i replaced those. do not have seat cutters but they lined up VERY close to original spec, so trying to get the seal back with lapping. it's working out, with one more touch up pass tomorrow, but there is an approx .0005" tall x .010" wide lip on intake valve face circumferences. this is splitting hairs, but i think i'll grind that .020" off the diameter right back to the gray band. that will increase the margin slightly, probably allow me to get a total seal (about 30* of arc was letting a few soap bubbles form with compressed air blown in ports), and i'll just dust off the bottom edge of the IN valves rather than radius them, based on both of your suggestions. the EX valves are fine and lapped in quickly, and already have a factory radius on bottom edges.
fluid dynamics... complicated subject but makes intuitive sense. you don't want air/fuel mix bonding to intake port walls, hence the rougher surface finish to keep the boundary layer moving. and over radiused valves could reduce some desired turbulence and dispersion as you mentioned 2M.