Conventional is as per Harley-Davidson with North/South cylinders, "side-on" is East/West. Most shaft drives I have seen have the crankshaft inline with the driveshaft & have inline, East/West twins/quads or boxer engines. I have never noticed a "conventional" V-Twin driving a shaft with the exception of Harley trikes. Keep looking - I don't know heaps about bikes & likely missed something.
Tons of the Japanese cruisers with a "conventional" v twin run shaft drive. If anything, the east/west v twins would be a rarer find (I can't even think of one off the top of my head).
Problem is most of the cruiser motors are bigger (1200cc up.)
If you go to www.mrcycles.com
they have all the parts diagrams for most jap bikes. You should be able to look up the exploded views of the gearbox output and shaft system to see how it all works and whether it'll work for your application.