Based off what you’ve said here, I think I’ve figured out a good bit of what I’ve done wrong -
So on the line going from the PCV valve to carbon canister, there’s a T joint that is pretty much right next to that lower port - I hadn’t noticed that the hose in the diagram was curved to attach onto the carb, so I was putting that line for the lower port onto the PCV line / carbon canister line instead.
I’m going to have a flick through the manual again tomorrow and should hopefully find a diagram that’ll show me where that T joint should be connected to.
Timing also 100% needs to be sorted out as well, should be able to tackle that tomorrow as well. Definitely feel like I should be on the right track now though.