i think it matters what age bottom end you use. if you use a later one that runs on a later form of fuel injection the dizzy is of a bigger size and of the wrong configuration so you will need the 2e dizzy. there may well be earlier engines that the pb engine dizzy will fit in to.
i am running an agg bottom end with pb head and a 2e dizzy and its great fun but i think i might need a new clutch now............
ps you might need to blank off some bottom end breather holes with either a blanking plate or some blanking plugs.
if you need any help just ask
