Petrol taps? They come from B and Q (plumbers' merchants) don't they, at about 4 pounds apiece with proper 100% leak-proof guts, with standard gas threads on the outlets, to be attached to whatever adapter one has on hand or can make if they won't go straight on?
Seriously, as long as petrol passes (or not, as the case may be) and there's a filter somewhere . . . A purist can always make better-looking levers to avoid any accusations of having fitted something yukkie off the hot water system . . . I have a box of these things and they are better - as taps go - than anything else I have paid far more money for over the years. As in they don't leak. Whenever an original of-the-epoch tap fails, on goes one of these cheapies. Nary a problem. I have a good half-dozen in operation.
I shall never buy another authentic expensive tap, ever, be it push-pull or lever operated and am unconvinced by the 'snot right' argument. (The larger ones also make very good oil line cut-offs to prevent dribbles going where they aren't wanted and becoming a flood in the crankcase, and can be fettled to provide a magneto earth switch with a bit of ingenuity.) Most bikes sport a weird mix of taps, neither of which is often 'original' and neither of which, equally often, works properly.