The 30 works nice with a pipe and mild porting. I'm not sure on the 28 but with the 30 mm, you will have to mod the air filter boot to fit but will still fit the Reed cage boot with no mods. You may have to use a reed spacer so the fuel bowl will clear the clutch arm.
now i just got rid of a 28mm it was a pian in the ass it needed jetted left and right and my 30mm on my paps bike is a oko and i never messed with the jetting your bike is similar to my paps bike i will get the jet sizes tht are in his carb so u will have a range of what you would need
f7 pipe trenga porting,pro design manifold,trenga reed spacer ,outerwears airbox cover,k&n /uni filter,+3 stroker crank,30mm oko carb thts a quick summary he has more done but tht is what i can think of off the top of my head