Never ran those tyres before so not sure what to recommend, but I would suggest starting high because it's easier to take air out than putting it back in, unless you have a compressor with you!
Something around 27psi might be worth trying initially. Do a few laps so that you get some heat into the tyres and then come in for a quick check on pressures and adjust if needed. You want the pressures at 30 or 31 psi when hot!