Hey Packrat, The earlier stator may very well fit physically in your 84 Aspencade but - why install a low capacity unit into a later bike. The number and thickness of the copper windings was increased with each production year. Just remember that the stator on the early bikes (up to the 1200) must not only survive the progressively higher electrical loads but do it within the innards of a engine bathed in hot oil. The primary reason Honda switched to a packaged alternator/volt regulator on the 1500 was for better cooling, improved current capability, longer life and simpler replacement.
The best replacement stator for the 1200 is the one installed in the 86 SEI (Fuel Injected) model. Although it is slightly more expensive than the standard unit, it is well known for having more copper and a longer life. You will have the engine out anyway - so to save some potential grief down the road you might also consider - replacing the clutch pack, rebuilding the clutch slave cylinder and inspecting your pulse generator coils (84 model) for corrosion while you have good access to the backside of the engine.