Hi Andy
When you find an old Z1 who needs a lot of TLC , work and parts to make it shine and to look like brand new you'll have to take in account that it'll cost a lot of money!
I've done this several times and I can tell you that you'll end up around 10,000 Euro only for the missing parts or for the parts that will have to be replaced because they're beyond the point of repair (original or repro) .
You have to add the price of the "bike" (at least 3000 Euro when you're lucky !!!) and the working hours if you can't do the restoration yourself.
When you do the restoration yourself I estimate it'll take you about 9 months of your free time. That is without the time you'll spend talking to your wife to convince her that you really need this or that "hard to find part"!
I hope I didn't stole your dream but it's better to know some figures before your dream becomes a nightmare or a bottomless moneypit
I'm convinced that , when you decide to do a complete restoration yourself, you'll find the information and help here on this forum.
Whatever you decide: Good luck!
Greetings from Belgium
Philippe