The good part of the bell housing is that it would be machined to suit the large bore 1st 2nd rod, if you use an earlier box you fit a du bush and then it suits the other type. This means that you can use any 71 series box except the early 240Z type. Any stumpy or 240K box, close ratio 260Z box or even an option 1 box from nismo if you're lucky. You don't need to go to a later double synchro 71C box but if you want you can. That's the beauty of the front case replacement. It is just like using a stumpy for your CA conversion... except it's your A series.

Anyway, it's a pipe dream unless I can get my boss to agree. And there is no way that I am going to get 20 housings sold on this site. Just being realistic.