Geoff, if you do end up making a small run of the short arms for the IWS bracket I'll gladly purchase one from you. I have had one of the longer 'J' shaped arms of an original bracket kicking about for ages, & don't in fact have a complete one myself. However, no worries if it's not possible, the other bits are more important. Have just wrapped up the gash Mk1 & Mk3 tubes for you.
Best.