My 1966 motor has the ball bearing on the crank drive side (67-1240) but I see the later engines (1967-68?) used the roller bearing 68-0625 so I can go ahead and just use 68-0625 instead? Anything else to note if making this change?
You need to provide for the end float. The later engines had shims between the roller and crank with a bronze thrust bush on the timing side. I presume your cases do not have the feature for holding the thrust bearing? A work around is to use an outside race captured roller with the single lip on the inside race then add a roller guide ring between the inner race and the engine sprocket. An NUP or NH bearing type
The crank is different dimensionaly so fitting a roller race will involve making up spacers/shims to centre the crank in the cases and have a thrust surface on the timing side. Problem with the NUP style bearings is they are only available as metric sizes so mean either machining the cases or the bearing. For a street bike just fit another ball race, they are good for at least 30k miles. Save yourself all the work.
Completely agree, I reverted from the roller to the ball quite happily on my 68', and will do this again too.