G'Day Musky. A good point to make about the cases. We all assume the motor will end up as a a high spec. A10, so no problem mixing and matching the bits.
Owen, The cases you need can be marked A7 or A10. They must have provision to bolt the plunger type gearbox to the back. Later S/A cases are no good to use in this build.
The cases you need for the more common shortstroke type engine have a trough under the camshaft. The cam followers are retained in the cylinder barrel, so easy to identify.
The earlier Longstoke engine is somewhat rare, being only produced for a short time, and has no cam trough. The tappet guides are located in the crankcases.
Longstroke A7 is a completely different engine, but shares a few parts with the later design, really just the oil pump and associated bits. Rocker Gear, Head, Barrel, Pistons, Crank, Rods, Camshaft, Cam Followers and Pushrods are all unique. Timing gears and breather are the same basic components, but timing marks and breather peg drive location are different to suit the longer stroke. All no good at all for your build. Primary drive parts were carried over to the later engine, and are well proven.
Good chance you have the later type cases you want already, but we all know about Sod's Law. BA Series Crankcases represent the last development in plunger crankcase design.
Cheers
Swarfy.