Gina - you mean did i do the sensible thing and protect the petcock from getting gummed up with sealant? nope!

but i was careful where i 'sloshed' it (my main concern was the freshly welded area at the top of the tank) and when i took the petcock area apart it had a bit of grub..but no sealant anywhere on it.
Oldroadie - from what i can see (i didn't do the welding) the origional pipe that runs from the bottom of the tank to the top is still there but blocked off at the top (i think he mentioned he'd welded it closed). I've pinged him an email to get a bit of clarity but i think that route's out unless he's only sealed off the top end and it can be snipped off.
or am i thinking of something else? (the vent at the bottom front right of the tank yeah?)
I'll check out the carbs next - never played with them before so it'll be a bit of a learning curve!
cheers guys