A few more updates to add since the last post.
1. I removed the brake pedal box and welded a new threaded stud into place to accommodate the new offset servo location. I also removed the link bar, the bit that connects the pedal to the servo, so it can be modified. It's currently gone to an engineers so that a thread can be cut to enable a new clevis fork to be fitted. I'll add some pictures to explain when I can.
2. I purchased (eBay) a set of R1 down pipes from a 2004/5 model that look like they can be modified to fit my engine/mini. I went with this year due to them having what appear to be a very compact design so have a better chance of fitting. They are also sectional unlike the 2001 version meaning I can unbolt the 4-into-1 and have it remade. The most important bit for me is the down pipes that attach to the engine head.
Pictures to follow.....