It's the quality of the steel that makes a difference, the older ones were definitely better but i have seen them rust out in the top left corner but nowhere near as often or as extensive as the later Chinese bases.
As for the adapter plate idea, it's already been done and i believe they were a factory item primarily used for base swaps for full cranks after the power torque came into production. (Well, at least thats what an old Victa dealer had told me)
I've got one here and if anyone is interested I'll dig it out and post a couple of photos of it.
