I just did this and thought I would share. Highly recommend doing this. Was not difficult to do, and my timing was WAY OFF. It was very retarded at 0.55mm.

I used this kit. Quality is questionable, but it worked fine for my very seldom usage. Really just needed the dial indicator and used the long M10 adapter/long coaxial probe included in the kit.

Additional tools needed if I recall correctly were sockets and wrenches in 12mm, 14mm, 19mm and various lengths extensions, and a wrench for the fuel pipes (17mm..?). One pretty long extension made it easier to take off the distributive plug bolt. You do not need to remove any timing covers to do this.

Here are photos of the FSM for the 2ct procedure:
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Here is an exploded view showing the distributive head.

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You basically take a bolt out, put indicator in, and then you are measuring the plunger travel from BTDC to TDC. Don't skip the cold start lever part.

Based on info from the old Ace Answers forum, I decided to go with 0.75mm. Do so at your own risk, as the FSM shows 0.73mm as the upper limit. I have noticed a bit better power, slightly lower temps. Time will tell what my MPG looks like.