Any chance you can make the proportioning kit adjustable from inside the cabin? I think alot of people would be interested in that. Myself included.

It can be done - that was discussed in this thread. You'll need an extra piece of brake line from your local auto parts store. The length depends on where you decide to mount the valve. It can be done without any flaring or cutting. The hard part is finding the best place to mount the valve, then you just have to run lines to it.