That's a good solid piece of British iron. The single carb will be much easier to set up than having to mess with and synch two Amal Monoblocs. The BSA twin engine was known as the power egg due to the egg shaped side cases. For a parallel twin they were smooth and probably more reliable than the competition. A very nice cafe bike could be coaxed out of that. You also have a really good drum brake on the front. Hitting that aluminum with 2,500 grit paper and then 3,000 grit, then billet polish will spiff it up right quick. Use WD40 as lube for the wet dry paper. BSA had a nice candy red color they used to use on their tins that I can see in my mind's eye on that bike with clipons, rear sets and a cafe seat.

When I relaced the wheels on my older bike (Kawasaki Z1A 1974) I ordered polished stainless spokes and nipples from Buchanans. Changed the whole look with that little bit of wheel bling.