Thanks for the offer. I really want to have karts in LFS when possible, and Eric does too as you can see with the kart tracks at Westhill. He likes to work from reference material when possible so your offer is interesting.
It's absolutely impossible to do it before the new tyre physics is working, for two reasons.
1) We can't add another delay to finishing the new tyre physics and graphics, for obvious reasons.
2) Karts don't work properly with the old tyre physics. I have some test karts in LFS and I use them as a test case for tyre physics. In reality, tyre physics works on a range from karts (or smaller) up to giant lorries, but the old LFS tyre model breaks down a bit when you go to those extremes.
So maybe we can talk again when the time comes. I can't give any estimates about when that might be.
The only sort of deal we can do is to put a car (or kart) in LFS without payments either way. We receive the reference materials / photos / drawings / 3D files / a lot of information about the setup and permission to use a real vehicle (without time limit). The vehicle provider gets some exposure in return, and that's about it.
We can't commit to anything at the moment, but it's an interesting thought.