When the D70 first came (and was availble in the shops - not on pre-order) out I took my D10 housing to the camera shop and tried to get the D70 in it. And I definitely made a post about it.
The D70 is smaller that the D100 so it does physically fit in the housing. The camera is a bit shorter - which can be fixed with a thicker baseplate. But then the trouble is that the lens is no longer in the middle of the port - which ruins the optics when using a dome port. This also means that you can't use an alternate back, Dave.
The other main problem is that quite a few of the controls on the back of the D100 housing do not match up with the D70 because they are not in exactly the same place.
I would suggest taking the D100 housing to a Subal dealer and seeing if you can swap it. It is new afterall and I think is more expensive than the D70 housing. Alternatively swap your D70 for a D100. I try and exchange the housing - this solution will be the least hassle. You may wish not to tell the present buyer - as they are unlikely to notice the difference!
Alex