Beachcomber,
Always great to hear from new members, welcome. If you've spent some time reading posts on this forum, you know that we thrive on photos of our member's bikes (not a requirement, of course). Sorry that I can't offer any experience with twin leading-shoe conversion.
For me, one question that arises from this is, "why did BSA return to 8" half-width front brakes for the standard Rocket Gold Star?". For the RGS, full-width hubs were an option. (I assume your bike is NOT an RGS.) I have some guesses as to the answer to my question:
1. The full-width rear brake was spongy, so, going with the rod-activated half-width rear, the half-width front was a better appearance match.
2. The half-width front was closer to "Gold Star" ishness.
3. As BSA seemed inclined to do, they had a warehouse full of them and needed to use them anywhere they could.
OK, I know this doesn't help answer your question, but maybe there is reason to stick with what you have, I'm assuming, a full-width hub. I'm pretty sure we will hear from folks more experienced than I about the conversion and it's benefits and shortcomings.
Richard