I think the difference between the 73 and 74-76 is in the seat cover pattern only.
I bought one for my 71, which came with the wrong latch mechanism despite having provided them with the year and VIN. Fortunately I had a late latch assembly banging around and switched it all over.
When I first got the seat it didn't seem to sit right on the frame, but after using it a bit it looks fine.
The quality is nice for the money, but not like an original seat. The pan is plastic, the rubbers that sit on the frame not as substantial, and the cover pattern is embossed rather than actually sewn in. Also, it comes without the Honda stencil on the back.
On the plus side I'm happy with the foam. It's comfortable and seems to be holding up well after a riding season. The trim and vinyl look great and I think this seat will last a while.
Overall I'm very happy with this seat. It cost nearly $275 with shipping, so not cheap, but nice original seats are fetching that much on eBay these days.