the 90spec car will have the plug you need, but it'll need splicing to your fusebox. call me crazy but if i were you id strip out the entire wiring loom from the 90spec and fit it to your car. the 90spec fusebox is better than the older one. main advantage is that all the looms are modular, on a 90spec replacing the headlight loom is a piece o wee, it unplugs from the fusebox. on a pre-90 the headlight loom is spliced into the dash loom and all over, right mare.
only thing is your car is a digi 8v, so the engine loom wont swap over, would need to get a 90spec engien loom or splice your pre-90 engine loom to the 90spec 16v engine plugs. im sure you'll be able to find someone who would want to swap a 90spec engine loom for a digi one though.
your call though, it is pretty involved 90specing a older car, fusebox hanger is different, column and stalks, clocks etc. the plugs for sidelights, indicators and horn looms differ too, though you'll have them on the 16v. just you need to find 90spec small bumper indicators from later spec carby mk2, unless you go big bumpers or splice the plugs to your old lights