The Rev seat conversion you are talkin about isn`t really to difficult to do, I had done it on my sled and ran it all last year it was an 05 seat, but if you the only down fall I encountered is the bottom of the seat is wider than the top of the tunnel and makes it difficult to stand with your feel back for long periods of riding feels like you are like straddleing the seat after a day of riding made my legs really soar the next day, the rev chassis itself doesn`t have this problem I beleive cause the running boards are wider and don`t taper back like the S Chassis does,
I beleive the best Rev Seat you can install is the 06-07 type seat like the ones you see on an XRS they are narrower at bottom and taper in to the top of the seat and would be much more comfortable, I have never riddin a Rev but at the dealer I sat and stood on a 04 Rev with the wider seat and then a 07 XRS on the same day and there was a huge difference between the two in seat design.
Here is a link to my photobucket to from when I built my Rev seat, all you need is time know-how and the from frame work of the original S Chassis Seat
you just modify the front of the Rev Seat frame to mate it to the original frame section and them wrap the rev upholstery around the front of the 2 frames and re staple it together, alot of people who have done this add a piece of plastic or something to the front of the seat frames to fill in the triagly shaped gap you get from the seat to the tank, You could also search on Dootalk for (Rev Seat Conversion) and you will come up with alot of people who have done it and pics also, mostly on ZX sleds but the concept is pretty similiar.
http://s375.photobucket.com/albums/oo197/ddcard/
there is also pic of my modded original seat I made after I sold the rev seat.
the rev seat pics are a few pages in in reverse order.
Good Luck, Wildcard28