Just in case you were not aware, the front end of your bike is off a Z1 and not A4 - different fork bottoms, caliper and disc. Also worth knowing, the discs on the US models (single disc models) were thicker than the UK models if you decide to convert to twin disc set-up.
Good luck.

Good to see that you have made a start. I'm doing a partial restoration on my Z900 A4 which I started last week. I will post some pictures of my z900 shortly after spending so much time looking at other peoples projects.
Is your bike an A4?

I can't find any info on the standard coils anywhere and am assuming from the reply from Boyer that the standard coils on a z900 a4 have got to be around 4.5 Ohms.

Here is the reply I received. It may be useful to other owners: Re: Ignition Coils Dear Sir, The Micro Digital systems are designed to run with contact breaker specification coils. This type of coil should have a resistance at the primary winding of about 4.5 Ohms. These ignition units can be damage...

You may be better off emailing Boyer as their telephone technical helpline is only available at specified times. You can get their email from their site. I sent an email to them last week re. which coils to use on my z900 with their micro digital sysyem and they replied within 4 hours.
Raf