I think it deserves to be Z/28
The original Z/28 only had a 302 due to Trans Am racing regulations limiting cubic inches to 5 litre v8 or 305 c.i.. The Corvette GT2 factory car in ALMS last year had similar regulations limiting engine sizes even though it was based off the ZR1 Corvette and in GT1 it was allowed to run the 427 c.i. 7.2 litre v8.
The 2nd gen Z/28 starting in 1970 was offered with the 350 LT1 and not the 302 like the 1st gen , the 4th gen Z/28 was offered with the 346 LS1, so it's not like the Z/28 has always had the 302 engine. The Z/28 can be any size but it must live up to the all track conquering car that history calls for. I will still buy it regardless of what it's called.