I will offer some advice, but there be plenty with differing views. You should bare in mind there is no guarantee the tyres are not passed their best. Presuming your concentrating on slick use only and they are not shagged then you should go aggressive on the spring rate, obviously the front ARB needs to compliment the spring rate. Personally I would be looking 300-350 front & 150-180 rear. If it is the same F3000 spec 13" Michelin slick that we all have used, they are a hard compound. They should be no higher than 21psi HOT, so start them at 16/17 cold and work them for 5/10 minutes before pushing hard. In my experience I never noticed any difference on the slippage between Radial/Crossply, if anything the Crossply bit more but hardly anything in it. Crossply certainly easier to get up to temperature. The set up is very important to get the best from these tyres, front camber should be high circa 3.5 degrees and at least 2 degrees on the rear, Castor should be high to maintain camber on turn in, ride height low with rake set to suit corner weights. That is how I set it for you anyway, all the best and good luck.