AFAIK Z33 and Z34 have massive space when it comes to fitting very wide tires, so much space that they would embarass Corvette of any generation. I'm pretty sure that your rear wheels and tires will fit upfront just fine. IMO 275 on 10" fits easily up front, on my previous 350Z, I fitted 275 on 10.5" up front and there was space left everywhere at full turns.