7/11 Basic guidelines

1.) First, when you go out to buy parts, try to get as many brackets, hoses, bolts, bushes, cables etc. with it. Those are the thing that will cost you a fortune if you have to buy them separately later. Better have them double for a small price, than having to buy them later for their weight in gold (because that's what they're asking nowadays for motorcycle parts).

2.) Buy a 1100 engine including carbs, all electrics including wiring loom, ignition (this is most important as the 750 and 1100 have different advance/retard curves witch will completely ruin your precious torque curve, and that's exactly what 7/11's are all about), coils, and preferably all switchgear. Also get the left clutchlever with the hydraulic pump when you buy the engine as 750's have a cable-operated clutch and 1100's hydraulic ones.
You don't need 1100 wiring but a 750 has a higher rev limit and the ignition curve may be different.Any oil cooled 1100 engine will fit any GSX-R750 that had an oil-cooled engine.

3.) Use a 4-2-1 exhaust to keep your midrange. Midrange has allways been the strongest point of a Suzuki 1100 and you don't want to ruin that by using a simple 4 into 1 exhaust.