87 forks are pretty ordinary. 88 cartridge forks go straight in.
Shock linkage/valving/spring rate is pretty whacky. Late KDX valve piston should fit and is a proper two-way valve.
Motor good. Mostly the same as the later ones.
Late model radiators don't quite bolt straight in.
Late model pipes/silencers bolt on.
Ergos a bit goofy - very dished seat, even by 1980s standards.
Plastics available from UFO.
Seat covers from MXM in the UK, but they don't fit quite right (too small).
The 88+ bike is definitely better, but I'd go on condition vs price rather than getting too wound up about the later bike.