Hi Nobby,
It is a similar basic carb to what I use, the jet numbers do seem to be high on that model, but do not be put off! I think you will have a 250 jet fitted as standard, but if the bike goes well you could be up in the 280 to 290 region. I would fit a 280 and expect it to be very rich on full throttle to begin with. At least you will be safe! work on bringing it down steadily.
The TMX jets are down in the 180 190 numbers and bear no relation to the ones you have for that carb.
Cheers,
Alan