Were all the 91 - 97 exhausts the same size/diameter. In other words are the end cans for the 600SS - 750SS and 900SS all interchangeable. Notice the earlier 750's had black end cans and i've never seen any high level cans on a 600 or 750SS.
early 600 / 750 (single disc) definitely have smaller dia header pipes in comparison to the 900ss, not unreasonable to assume these silencers are not compatible with 900, just put a tape measure on my 900 silencer they're a gnats under 43mm OD entry, maybe someone could measure a 750 pipe end for you. only the 900 superlight left the factory with the high level pipes as standard, all other ss variants had normal (lower) silencers, in single or pair.
Hi level pipes can be bought easily enough. Cans are universal-ish depending of course on the diameter.
I've fit a high level Sil Motor can to my 600ss with 750ss downpipe. The l/h exhaust outlet removed and blanked off.
I run Hi level SL cans on my 750... for a high level on the 600 i used a FZS600, viper link pipe with whatever end can I fancied...
Hi level pipes? Here ya.....these are on my 750......the same system, but I changed the can covers from ally to carbon. AL