Yes, the drive shafts should be pure Fiat, but bear in mind the Model 70's development goes way back into the time of the Fiat 500. Indeed, the early prototypes used the entire mechanics of a Fiat 500 as in hubs, radius arms, suspension, drive system, gearbox and engine. Production Model 70's have a unique gearbox mated to the flat-twin Styre-Puch engine, but this was originally fitted to a Fiat 500-based vehicle itself, so both ends of the driveshafts sound like they should be standard Fiat. As time went on and the 500 gave way to the 126, I would have expected the Model 70 to have followed as regards swap-over of parts if there is any difference between 500 & 126 in that department.
Keep poking me on the hubs if I don't respond timely. I think I've got a list of certain parts used somewhere and what they were from, but I can't recall if it included brake drums. Again, historically, the Model 70 used 12-inch wheels up to around 1974-75 and then went down to 10-inch Mini rims thereafter, so that might be why the drums turn into something weird.
If anyones got any at the moment, It'll be Barry!
Judging by the dates on the Morris Minor repair kit, I'd say it's for older, Villiers-engined cars (Stop looking Bob!) Plus, be careful of falling into the trap of calling ALL invalid three-wheelers "Invacars". The Repairers never did it (not proper ones anyway) so shouldn't we....