40mm is a lot. Extending a standard fork is usually possible to some degree. It's probably possible on a USD fork as well but for sure more complicated. (Unless it's non adjustible then you could probably correct that with higher end caps you'd need to fabricate)

Indeed, the Sport has pretty slow steering, so shortening the forks will certainly speed up the steering. As long as you don't bottom out anything. I have my forks slid as high in the triples as I can get them and not have the forks bottom out. I did have an issue with one of the fenders that I had on the bike that actually hook onto the opening of the fairing on a hard compression slow corner. Did not crash, but was alarming.

Changing to 17" wheels will help with the slow feeling on the Sport. If you can, find a 4.5" rim for the back and run a 150 tire.(common on 750 SS and Monsters) If you already chose a 5.5 rim, then run a 170 on the back. If you run some V shaped tires, like the Pirelli's, they will turn in quicker also. The Michelins and Metzlers have rounder profiles (generally) and will be a bit slower steering. Conversely, if you put Pirellis on a SuperMotard, that may be too twitchy.

Of course, as you speed up the steering, the need for a steering damper starts to come into play. I put one on, but mostly because there was evidence that the bike had experienced a tank slapper in the past.

I agree with trimming up the rear fiberglass/plastic. I think you have a good start, and need to continue trimming. That rear frame looks really nice and should see the light of day.

Cheers, Phil

Summit racing has some.
https://www.summitracing.com/parts/mio-mmcp-2090bk
$9 for silicone is a good price.
Get a short bit of aluminum 2" tubing to make a joiner to some 2" air cleaners of your choice. You end up with 3 hose clamps on each one, but a pretty good laminar flow that contains the fuel fog at low speeds and some really good breathing for top end.
Here's some aluminum tubing from the same folks. Nice and smooth for intakes.
https://www.summitracing.com/parts/vpe-2885/overview/

but first, check to see what size tubing fits those carbs you have. I have Dellorts with the gray plastic velocity stacks on them. They have a 50mm OD, which 2" works fine. Actually, its a pretty tight fit, which is good. Not sure what OD size those carbs are that you have.

I cut the elbow on the carb side so that the outside of the elbow rests on the other head, and helps to support the carb and air cleaner a bit. Its all a tight fit, but works out pretty well. Tin snips work well to cut hose like that.

Cheers, Phil

Got the valves and new belts adjusted, rebuilt the clutch lifter and added new clutch plates. Repainted the Brembo calipers and discs. Also did a bit more on modifying the rear end, Going to with aluminum exhaust hangers (to delete the passenger peg mounts) and possibly some new slip ons. Will 900 or 750SS slip ons fit the stock headers? I am having the stock headers ceramic coated black but will hold off on having the slip ons done if I can pick up something else.

Thanks

Header diameters changed through the years, and frankly, I have no idea what the stock pipe diameter is/was, or what fit to them. I have some funny little adapter pipes that go from smaller to larger with a squiggle in them. Glad to contribute to a worth cause. Let me dig them up and get some dimension on them, and some pics posted.

Lots of progress on that bike. Looks great.
Phil

Nothing too exciting to update. Finished the mock up and dropped all my hard parts off at my powdercoater. Rebuilt the 40mm front brakes and waiting on the rebuild kit for the 900ss rear brake. Also freshend up the front discs and ordered a bunch of parts.

Looking good mate.

Engine is ready to go.

Wow, that looks fantastic. I don't think it looked that good 27 years ago.

Phil