I have the whole 90 1100 front end and rear tire and breaks on my 86 750. If you go that route its cake. You just bolt it all on. If I remember right you need some risers for the fairing stay that goes between the mirrors.
I've got a '90 1100 front end and wheels on my 750G, too. It all does bolt right in, except that the 1100 bars are above the clamp, so the master cylinder will hit the fairing. Just use 750 bars (under the clamp) and you're good to go. The rear wheel can be used with the oruginal '86 axle. Here's a link to a CBR wheel swap, in case you haven't seen it.