I can only think that would be interesting to a lot of owners to allow them to get around the infamous front prop shaft rumble on long runs. Of course, you'd want to sell an LED conversion with it for the diff lock light as that melts the warning housing in the dash if left on too long.
If you want some spirited response and to generate the interest to make economy of scale more viable I'd suggest posting it up on the forward control club forum. I think one of the club comittee posts up very occasionally over on Pirate.
101 club forum
Mind you, we Brits are a tight lot when it comes to our Rovers so expect a lot of people to whine when cost is mentioned. It does strike me as a far simpler and hopefully cheaper solution than rolling diffs, fancy prop shafts and 2wd linkage conversions to an LT95. I'd suggest offering them a production run of those disc brake mounts you did too.
I'd be interested to see them but right now I'm mortgaging my left kidney for my 109 build.