Looking at Clive'e big picture...this is my suggestion:
LS1 Z: (track days)
Keep the LS1 Z (EvilZ) as is. It is pretty well dialed in and has all the parts that anyone would ever need on a Z, Patch up some minor rusty panels, have the cage welded in place, cut the fender lips off and add some BAMF ZG flares, throw on a coat of "track day quality paint", have the wiring neatly cleaned up. DONE. Track car with streetability.
Bob Sharp Special Red Z: (profit maker)
Clean it up with detailing, get it running with carbs and fuel system cleanup, put a history log book together with all the awesome history Bob Sharp papers and catalogs that came with the car, Sell it for a 100% profit.
This New Z: (turbo street show sleeper)
Use the money from the sale above, fix the minor external rust on the car with welded panels, paint it show quality, put in the turbo motor and an R200, put in some basic street performance part suspension, and nice wheels. Keep it stock in appearance.