The rims sound like standard rims, meaning it's either an SE, or could be an R with a dry clutch engine added in. The color of the forks don't mean much, some of the R's came with black, as did some of the SE's and SP's (91 and 92 had them mixed).

From what others are saying here, 2300 GBP seems a little high for a standard NSR (No trick bits to make it all fancy like). But others in England can give you much better advice on that.

Now in the US that price for a decent model anything with valid title would be a good price.
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Charles Gallant