Some things I noticed concerning fuel etc..
Smell of petrol in boot/in car?? Blast of vapour when removing filler cap?
If so and your rear window surround seal has been leaking many years, your fuel tank could be well rusty underneath, you can't see this properly until you remove it. Welding 
the hole is a good way of blowing yourself up (email me privately if you want to know how I weld a tank without explosion). Noisy fuel pump? Gets louder?? Blocked filter in the intake!. Vacuum in the pump causing cavitation. The filter is plastic gauze, push-on fit, a bit fragile. Kettle descaler, followed by a dishwasher cycle cleared the filter gauze and restored quiet operation after refitting. Tank draindown needed before removal. Can get away with pinching off some relavent hoses with molegrips to reduce the amount of draining needed.
but I have bought the filters. They are the metal/glass ones that I think may be designed for WW Beatle engines. I didn't like the look of the plastic disposable ones, I wouldn't want them leaking in the boot! Due to the small diameter of the inlet/outlets I worked out that two units plumbed in parallel may be sensible. All I need to do now is work out how to manifold them together with suitable valves to make cleaning them easy.
