I've been
trying to sell a pair of the 370Z heated leather touring seats and I've had a couple people ask me if they will fit the 350Z. Here's what I've learned:
The bolt pattern is the same but instead of there being an alignment pin on the floor it is on the seat bracket on the 370Z seat. All you have to do is cut it off and then drill a hole in the flange to fit the alignment pin on the floor of the 350.
Good news is the reverse works if you want Z33 racing seats in your Z34.
It turns out the issue is that the seat belt and airbag wire plugs are apparently different. Expect to rewire the connectors. The seat belt latch on the 350Z is also slightly wider. The latch from 350Z seats can be moved over.
The 370Z seats are very slightly wider, and have more adjustment in height and lumbar.
Or, you can swap the entire seat pan (lower frame) between seats. Honda guys do this all the time; there are lots of instructions and videos out there.