It's a 1098 R isn't it? See if you can get std 848 rid length, that seems about right for 1098 too as a starter
IIRC the 235 "standard" measurement harks back to the 748/916 etc and as the overall geometry hasn't really changed (swingarms got a bit longer) it follows over. However most seem to have been setup from the factory a fair bit lower at the back as the position of the seat on the 1098s is quite a bit higher than the older bikes and "optimum" geometry at the rear makes it really high. There's a good article on it somewhere I'll try and find it :Bookworm:
Got my new chain and sprockets on now. Rear wheel fits with a 98 link chain! Left the suspension rod at the setting that it was already (175mm). Adjusted chain (eccentric at about 5o'clock) and measured the height with the tool I got from @bettes (cheers!) and it came out at 228mm which is in the right ballpark. I will leave it at that for the moment and see how it feels. Cheers to all for patience and advice! R