Well, I did this today, and I wouldn't recommend it! Bought a nice aluminum perch from local "real" bicycle shop. Unfortunately, their cable ends are 7mm, octane is 6mm dia x 10mm length barrel end. So I had to shim that. Coors beer cans make excellent .5mm shims!
I had to cut the big honkin' cable end adjuster off of the stock cable, as it was about 2x the size of the threaded insert to the bike lever perch. Then, that caused the cable to be too long, and the remaining adjusters (the one by the carbs, and the one on the bicycle perch) couldn't take up enough slack. So I wound up bending the crap out of the lever, to try to get it to throw enough to open the carbs fully.
Finally, I gave up on trying to bend the lever, and moved the cable to the second slot on the carb (my stock carb has 2 spots for the cable, almost looks like it was a "push-pull" setup for a motorcycle throttle originally?) That got the slack out, and put the length in a range where the adjusters could work.
Then the lever hit my other fingers on the bar, so I had to cut the lever back to where it only fits 2 fingers.
On the plus side, now my Octane has an idle! I just adjusted the cable to hold 2800rpm out of the water.
I'm actually pretty happy with how it turned out, but it was hours and hours of fiddling. If it wasn't for the fact that I need this ski running on Wednesday, I would have gladly paid for a nice Umi setup...