I had to swap bosses with Cliff Pett when I had his 280ZX and he had my Z31 turbo. We both had the same steering wheel, but couldn't just swap the whole assembly...
No! It is the splines on the bosses which are different - 280ZX spline is in common with 240Z / 260Z; Z31 spline does not fit 280ZX...
What make wheel do you need to fit? I can get Momo style bosses for early Z/ZX and possibly Grant and Motolita versions. Also have a Momo to Grant adapter in stock if you have the boss for one and the wheel for another!
Alright - I don't like the 280ZX wheel and would like a leather one ! The Z31 wheel I had on mine ex-car would have been fine ! If you can suggest (by photos and price) some others, I'll consider ! Perhaps we'd better do that on your forum bit ?
Have a look at wheels on http://www.zcarparts.com
They come as complete kits with appropriate boss and "Z" logo horn push - can add to any USA order. Beware, if you like leather, not all leather look will be real leather - sometimes Naugahyde...