Help me strike a staking deal!

[pofigistka]

A friend has offered to stake me on Ultimate bet for 100max (6 max) and 25c 50c heads up, and i would like to take him up on this.

After 13,500 hands at nL($1) I am running at 7.5 ptbb/100.
After 20,400 hands at nl(0.5) I am running at 14.5 ptbb/100.

There is also my 30% rb deal to take into consideration, as well as the points for cash promo that is running.

What would be a fair percentage for my pal to take? We want it to be a fair deal for us both.

We envisage him taking sole liability for any losses and taking a share in the profits that reflects the risk he is taking.

Also, any other tips/suggestions?