Over the last couple days I've been removing the carby and inlet manifold (So my mechanic can look at my manifold) where I noticed the brown stuff above #3 cyclinder (see pic)

Would I be correct to assume that would be a sign of the inlet manifold gasket being blown?
 
I'm really hoping that the gasket is the cause of the major running issues I've been having, but also going to removing the elec dizzy for my mechanic to have a closer look at.

Scott do you have an auto choke? It looks more like its had a split hose where it would connect to the auto choke.
 
Rhys

Its also hard to tell from pic but manifold passing dirty water like that should be pretty obvious. Also check manifold mating face for any corrosion through gasket mating area.
 
Rhys
 

Yeah, it's an auto-choke setup, I'll double check the hose tomorrow when I go to take the elec dizzy out. The mating face area is actually one of the things I'm checking, I have been meaning to flush the water system so I'm already aware of the ;)

The staining is too high for it to be the manifold gasket and that all looks pretty clean around the water hole anyway.  That will either be one of the hoses running to the choke or the choke mechanism itself on the carby leaking

I just checked the hose, it's completely fine. The choke has barely worked in years, but car ran fine so I never bothered to fix it.
 
Now that the dizzy, inlet manifold, and carby are now out, I can have a proper look and hopefully find the cause of the problem. Mechanic suggested possible vaccum issue, or manifold cause problem, or the custom built electrical dizzy, or the ignition system (got kill switch). So yeah a few things to check.