Don't mean to be negative... but for a Z, thats super low. If you already had all of the equipment to do EVERY step, then it might come together within a year for 5k. There are just so many things on a Z that need replacing (or really any car of this age, but especially Z's) I mean, have you thought about something as simple as weather seals? 90% of old ones are screwed, and a full replacement set is $700. Something very basic and often overlooked, but very crucial! and this train of thought will apply to more than half a dozen parts where it's borderline...
I guess for that amount you're better off buying a near complete project or a project that isn't sought after (like an engine swap or a horrible colour) but you will be waiting around quite a while...
I hope this helps more than it puts you off.
My project started off at around 10k with a good estimation. Fiberglassed over rust blew that out to way over 20k and more than 3 years in the making and counting.