Murray
Yes this is a pretty easy modification to make and a much safer option as long as you steer clear of the Pro Drive System. Apparently it has a higher drive sprocket which increases the bending moment on the Cantilevered Secondary shaft as well as running a very (TOO) high tension on the belts.
For my safety and piece of mind after doing many many hours of homework was the AP Heliproducts designed belt drive system with a hydraulic clutch and belt tensioning system which can all run with the Factory 35 mm Secondary shaft or be used in conjunction with the AP secondary shaft system as well. All up the modification run around AU$ 10k -12 k plus duty and freight.
If you need any more details check out their site;
http://www.apheliproducts.com/
This was the point where Iwas up to 15 months back and had to decide if I wanted to invest this much into the current system or use this money and that obtained (hopefully) from the sale of the new engine towards a turbine project where the turbines were around U$5K and the KISS Kit U$ 23 (EPI kit is still not available but projected estimates are around U$18.5K for what I consider a much better designed sytem with the turbine mounted nuch lower inside the existing framework rather than tacked ont othe top.
Given the unfortunate delays in the EPI system I and a couple of other turbine owners are collaborating on an alternate drivetrain that just might suit our purpose,
Give me a call if you'd like to discuss things o7 4124 2329
Peter.