Thanks for the advice all, I think I'll have to take the carbs off again.
I stripped them down and gave them a blow through with an air line and some carb cleaner when I first got it, but I've since bought an ultrasonic bath so I'll hit them with that.
Seemed to start a bit easier last night, but not great. Incidentally, I thought I'd give the Starfire in the vid a prod seeing as it's sat unloved for a few weeks over Christmas with no tickle charge, fuel stabiliser or anything. Started first kick, so it can be done!
Really pleased with the lightning though, it's pretty damn rough, but that's what I was after, something I could bring back to life and do my own thing with. I also have a Bonneville, but it's in such good condition I'm scared to use it too much or do anything too obvious, apart from sensible upgrades to clutch and brake, etc.
I'll put a bit of a build thread up if anyone's interested. Hoping to get to my local meeting too (Norfolk).