Well, good news! Work decided they wanted to actually me to do some, so I had to leave this issue for a while.
New float bowl gaskets ordered from a local supplier (Sussex Marine Supplies) at a very good price.(£7.90 inc P&P)
https://www.ebay.co.uk/itm/Holley-Non-S ... 2749.l2649
Fitted, a couple of hours checking and adjusting MOT things, and a first time pass! Not bad for a car that has been sat standing (in a garage) for around five years! Very happy!