When you switch an early bike with scrolled rockers and back-feed oiling to the later style pressure oiling then you definitely need to install the plain rocker spindles otherwise you will have a massive oil leak in your head.
The other thing that was done when Norton switched to the faster oil pump gears was to enlarge the oil passages in the pump, cases, oil manifold and pipes so the higher pumping volume could be utilized more efficiently.
I recently put a 650ss engine together with the faster gears and there are some photographs of the early and late pumps and the work I did on the oil passages here:
http://www.facebook.com/media/set/?set= ... 123&type=3
You can read about the modifications that Dunstall did to the oiling systems of Dominator racing bikes in the papers here:
http://www.facebook.com/media/set/?set= ... 123&type=3
Heinz Kegler, ex Norton experimental department and head technician for Berliner said that he flips the rod bearings upside down and blocks the oil squirt holes in the connecting rods. He said it was a band-aid fix that was not necessary after other things were fixed.
If you can get your hands on a late 60s Norton engine to take apart and look at you will see what parts and machining they changed on the later bikes.
I did throw a set of 6-start gears into an early Norton with no other mods before and it worked fine, but that was because the back-fed rocker oiling was kept. I am sure it had a lot more oil trying to get places especially at low rpm. I am also sure that it would have been happier yet with all the oil passages checked out and enlarged. Good luck.