VX 800 : love this bike - but want a taller gearing for Cruising

first of all: new here - traveling with a Suzuki VX 800 (among others). Looking for a long 5 gear for this -
Alan - a Canadian did this once and used a GS engine here.

Quote :

The biggest part of getting the 5th gear made was knowing that the internal of the gear was the same as Suzuki GS models.
After that... there needed to be a very tiny bit of the shift fork ground out of the way.

you can help here.
btw: More information about Alan's gearbox modification here: 
srry - german text  - but no need to be looged in
 
so the question is : how to proceed - how to find the long gear for the suzuki VX 800 
I'm happy to hear from you.
regards
 
see some more details
 
the VX 800 data: 
Gearbox Standard: (1 -> 5: 2.285/1.631/1.227/1.000/0.851.
Gearbox Custom: (1 -> 5: 2.285/1.631/1.227/1.000/0.75 - > this is wanted - i want to have the taller 5. gear

alan: - on the VX800 forum - link above:
 

Quote :

This project has been a long time coming. I am not an expert, nor do I have an engineering back ground I have just brought all this information together to make it all happen. This is my adventure…..I finally got a final drive from a VS1400 Intruder installed. The hub ratio is 2.66 vs the 3.09 of the VX. Approx 14% taller gearing throughout all gears.
Top speed is not effected, as it is now too tall to rev beyond 7200 rpm (or 110ish mph). This is with a new Avon Storm 150/80 on the rear.
The rpms are lower in all gears. At 60mph I turn 4200ish rpm and 70 comes at just about 5000 rpm. I have only had it on for 2 tanks of gas so I have not memorized exact speeds. These are approximate [...] 

I just learned the modern Suzuki VL800 C50 has a taller 5th gear at 0.814 (and a shorter 1st gear at 2.461). I haven't confirmed, but I'll bet the parts are a straight swap. If they are, then 1st gear at 30mph will be 250rpm higher and 5th at 70mph will be 150rpm lower