Yeah it had to be something with the pump... IIRC i even went as far as removing and refitting the pump, but the problem remained... Didnt go away until the engine was the right way up.
I was in a real rush to get it back together too, thats why i was prepared to say "Fuck it, do or die". It was a saturday and i was booked on track at National day 8 days later
It was running by sunday tea time, done 600 miles by thursday night, got the fuelling checked on friday and off to Donno on saturday afternoon That was 2002 and its still alive!

I can see how funny the upside down comment was
I was assuming the engine was out and on a bench, not upside down in the engine bay LOL