Sounds simple enough, just looking at options.
I see the 88 has shorter stroke bigger bore!
?
86mmx86mm all years
main differance between 88 and later year
1/ different barrel%and head {no center kips on 88}
2/ slightly differant angle on the carb boot
3/ lighter flywheel on 88/ differant stator cdi coil
4/ slight differances in cases / 88 has more case volume and no hole for the centre kipps
porting specs are very similar all years 1986 on
Advantages of the 1988 barrel /no issue with cracking exhaust bridges / bigger water ways and bigger kips chamber and a smooth exit out the main exhaust port {which suit anybody looking to go bigger on the bore