The NF5 frame is probably 5 degrees or more steeper, sitting physically quite a lot lower than the NSR at the top mounting point for the rear shock. The frame is also shorter, and the swingarm longer, even though the wheelbase is almost identical! All of this will make the projected seat angle much higher, and further back than on the RS.
In short, you're just going to have to take the plunge with the saw! Take a small amount off at a time. If you want to keep the access holes at the front of the seat, then you're really going to need to hack out a small "v" (probably at the narrowest point somewhere under the seat pad), and then glass it all back together and smooth the lines out. It's not going to be a 5-minute job.
Racer38 fitted a 1993 RS seat to an R5K many years ago, which looked quite good, but even that looked long. The photo may give you an idea for yours though.
You can still see how the seat doesn't quite line up, and how it needs a section cutting out at about 5 degrees... If you cut from the corner where it intersects with the tank and frame back to just above the mounting hole, that would probably tweak it just enough. However, given the longer NSR frame, there will still always be a lot more over-hang at the rear.
A (very) quick Photoshop hack to demonstrate what I am trying to say...
Looking at it now, rather than taking a V out under the seat pad to further lower the tail/angle, maybe taking a a parallel cut out to actually shorten the seat would work. Can't be arsed to fiddle around with Photoshop again (seeing as that's not even the same seat), but I imagine you get the idea. If you mocked yours up the same, you would have an idea where it needs cutting!
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Andy.
NSR-WORLD.COM
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