Yeah I'll get a vid of the vaccum gauge but it does seem to be jumping at idle and cylinder 1 seems to do nothing. It is making a rattle at the front of the engine aswell. For the crossfire test do I just spray water at the dizzy?

They clatter like nobody's business. Could be a sticky intake valve, but I'd expect to hear valve-train ticking?   A vacuum gauge, would show a sticking intake valve as momentary positive pressure. (needle would flicker to low vacuum)  

The engine sounds healthy, it's just missing on one cylinder.   @deankxf, I'd check for spark leakage in the dark, with a spray bottle of water.   And also do a cylinder drop test - with engine running, remove/refit each plug lead in turn at the spark plugs, and listen for engine note change/rpm drop (advise to pre-loosen all leads before starting engine, then use gloves/pliers to avoid zappage)

I think deans on it, only other thing it could be is a valve not seating

@Thom reckon this sounds like  cross firing (crap dizzy cap or leads) or a sticky valve..  seems to run smooth at some point so it's surely not a pushrod?  what's a sticky lifter do when they go bad?

definitely odd, my first thought would be to look at the dissy cap for cross firing (you can do this in the dark possibly, as Dad's 351 was like one of those millennium balls at night when it was sprayed with rusty water from the radiator)
   

That's a video of the popping

My phones being a cunt but its making a poping sound and can be best heard through the carby. Its worst when its under load and now it runs like crap all the time at all rpms. Do you think its over for this engine?  

Sure Ill get it to you

Any chance of video and put it on YouTube 

Thought so the rattle only comes on past 1200