[Alan L]

Thats a cool looking car.
You are on the right track.
There is a vac line to the dizzy that only works when the car has warmed a bit. It keeps the timing retarded early on - so that may be the one you are talking about. It is plumbed thru a thermo switch.
By all means check the dizzy - your vac adv/retard may not be working - they do fail. When you get the dizzy out you could check it if you have a Mighty vac - that will give you pressure and vac. There is an arm that runs from the vac can to the mechanism below. You may be able to see it by pulling the rotor and the plate that sits below it. It should move with Vac/pressure.
As for pulling the dizzy, yes - helpful to get to Z1 (#1 firing). There is a notch on the body of the dizzy for the rotor to line up on (so you dont confuse with #4). It should be pointing at about 2 o'clock. It may be hidden by the plastic cover plate on the dizzy base. When you have Z1, pull the dizzy - just that 13mm nut at the adjuster base.
Hint - I use white marker pen and mark where the timing is set now - on that adjuster base. If the timing was right, saves a job later.
The dizzy drive gear is helical. So the dizzy rotates when you pull it out. So you need to compensate for that when you put it back. Trial and error will tell you when you have counter- rotated just enough to engage the right tooth for the dizzy. It will land back at your 2 O'clock.
Alan
PS - if you make a plug tool like mine, you can get all the plugs with everything intact, incl the intercooler. I could give you the length of my unit but that will likely mislead. Unless you have exactly the same plug socket, the internals will be different. But you want the head of the bolt to sit near flush with the cyl head - just enough poking out so you can grab it with your fingers.