tire pressures for dunlop gt501F on 76 KZ900-A4

Newbie here.

I am not sure what pressure I should be using on my Dunlop gt501F tires. I do a 50/50 mix of highway/city driving.

Kawasaki user manual says 28psi front, 32 psi rear, but that's for OEM (tubed) tires.
Sidewall says 42 psi max (front and rear)

Am thinking of going 32 front, 38 rear... but that's just a guess. Anyone got suggestions?

Thanks.