X2 on what sdkar said...My Z didn't come with power steering. Previous owner/s, don't no who or when, had installed a crappy, leaking 67 box that I changed out for a 1980 WS6 Trans Am power unit (I got it for free, and could have gotten the disc brake rear for free too but stupid me didn't want to put it under my Z). Someone turned me onto the guy that does the NASCAR power steering (can't remember who it is now) and he sent me the inserts I needed to install stock GM standard flared end hoses. If I remember correctly 1980 was the last year for standard threaded hose fittings and 1981 was when GM went with metric fittings. I do know the 1980 boxes are standard because I just installed new hoses I bought from Ricks 1st Gen for a stock 69 box. The turns lock to lock is just under 3, maybe 2 3/4 turns. The feel is tight, positive and very deliberate and will take some time to get use to. It did for me when your use to 4 turns or less.
Something else to be aware of also, I had to change the coupling at the steering column to fit the splines of the 1980 box. It's been a few years now but the splines is actually smaller and won't actually fit the stock 69 column coupler. If I remember I had to get one for a 1977 power steering box to fit to the 69 column because the 1980 was a bit different where it attached to the 69 column flange. You get what I'm saying here don't you?
Ask your builder if he can build it to 1980 WS6 Trans Am standards and you may not have to go thru all the other parts change outs. You won't be disappointed.