The brakes work fine but the pedal isn't great/as good as it should be. The footbrake is a very good indicator of how much the rear brakes need adjusting and mine is right at the top.
I've had a firmer pedal already during this saga than I have right now. I'm not going to give up, or settle, as I've done too much already for that. Will see how I get on after I replace the brake booster. I'll also probably check the MC with another bench bleed, but I'll put teflon tape on the plugs this time and see if it really is drawing in air or not.
If I still have my original MC (Can't remember if I used it for a core or not) I will use that reservoir with the AZ Duralast MC I still have and prep it in case I need to use it.
Thanks for everyone's support and advice.