Leaded gas doesn't matter to your cats, since your catless.
Leaded gas can muck with your O2 sensor, but you're not doing it that often. I've had all my past cars mix 91 octane + 110 leaded (at least 20 tanks worth - trackdays) and never had a problem. Its not a guarantee, but if you're only doing it handful of time, I don't see a problem.
(and the PROcede can be set to whatever setting to my your ECU happy with the cat status).
email@example.com (1.641 60') - AutoTune 7-27, Race+Meth, Best ET w/ only 80% throttle 1st and 2nd
firstname.lastname@example.org (1.590 60') - AutoTune (beta pre-5-15), Race Gas, No METH
Perf Mods: Vishnu PROcede Rev3 v5, Vishnu PWM Meth Kit, AR Design DPs, AE Exhaust, Helix FMIC, Vishnu DCI, Forge DV, WaveTrac LSD (Best Trap - 124.665mph)