Yes, definitely drive it as is and work on the suspension, brakes, etc first. You need everything in good working order before you have real power anyway, and the Z's stock 170bhp is pretty fun as is. I always drove my basically stock L6 77 about 10x harder than my turbo 78, because I didn't have to worry nearly as much about losing control.
Then, when everything is running pretty smoothly, go buy another Z, and prep that one for an engine swap. You won't ever want to have to drive a civic every day once you've been driving a Z.