Just watched a video of Clone medium race It's advertised at a 1/4 mile and based on 18.5 sec lap times that's close, based on that only NO tried and true info I'd roll in there with a 19/65 and go from there, hard to tell how well it grips up so have an 18 driver ready If your to low on R.P.M. drop it to the 18 front.
Hopefully someone that has raced up front there will confirm.