Thanks Mike, the heads are Edelbrock RPM and they've been on the car since 2006, gaskets as far as I can remember were the blue coloured Fel Pro ones in fact I can see a bit of the nearside one looking like it's been squashed out between manifold and head, it's as if something's moved,very odd.
The manifold came with the carbs from WeberCarbs.com at the same time, I've had no problems at all with them apart from the obvious tuning to engine which is a 347.
I've just pressure tested the cooling system and it holds up OK at 13lbs but that's with the engine cold, but it's obviously been leaking at some stage.
Which gaskets would you recommend?