Largest pinion possible with RCM Xray 808 mount?

[SidewaysLS4]

I have this idea for an 808 based speed machine, but with the low geared diffs and my smaller tire spec (Belted OFNA or Ipanema tires), I would need to speed up the drive train some with the stock gearing it would seem. Any ideas how big of a pinion will work before the RCM mount runs out of adjustment room assuming the stock or -1 tooth option spur?