Is a 68 tooth rear sporty pulley a straight bolt on for the late dynas?

cheers Hilly. I don't have any spare pullies to check against. It seems like it should fit, both have the same width belt 1"

much drama in changing the front ?

cheers.
looked like a bit of stuffing about and may need some tools to do it with out risking damage.
68 it is then.

that would be a nice problem to have to deal with

Yes BUT depending on the height of the rear sus, it may cause the belt to just touch the frame over some bumps. I made a spacer for mine.

cheers will check that