classic motorcycle forum

The bevel drive problem is another Net myth, isn't it? As I understand it if you use the wrong/no oil it soon wears, but that goes for most things.
Should think the Urinal (fitted with some real ball races) bevel would last well though.

Any pics available?

My advice would be to get it running first, then worry about the appearance and possible up-grades. When it's running OK you can then decide what it needs (or what you want it to have) otherwise you're just chucking money at it because some bloke on the 'Net said so.
Most unwise.

I'd be interested in a typical ball-park figure for a tank too.

Stoppit, or you'll have that Johnny Boy bloke down on you again....

Always makes me wary when someone describes themselves as an "engineer" when they're selling a bike. "Engineer" is a broad term, and while he may be a time-served skilled mechanical fitter (in the true sense of the word "fitter") he could also be someone who services dishwashers, installs software upgrades or even designs space rockets, none of which would give him any skills or insight into how an old engine needs to be put together.
Then again, the old joke about mechanics' cars is very true too...

Looks like it's coming on well though.

If he's a big knob in the BSA club then I'm glad I sold my last BSA some months ago. He may be right or wrong in his understanding of the pump and valve workings, but what a condescending arse he sounds.

Without knowing where in the World you may be, it's impossible to say. A search of good old Ebay (include finished sales too) should give the best indication.