66 on the bottle

ok i am running a 355 ,scat crank,scat rods,trw forged flat tops 10.1,comp cams nitrous cam mild,torker intake,750 holly,mallory mechanical dist,mallory coil,mallory nitrous 6 box.my question is should i lock out my dist?i currently run my timming at 36 total advance and have my box set to pull 6 degrees of timing out when i hit the button.i tied to run it at 38 total but when i would hit the button i would get a backfire,i am wondering if it was from my distributer not being locked out.i am running a 150 shot on the nx hitman system and fixing to bump it up to 200.so do you think that locking out my dist would be a good idea,my nitrous 6 box has a starter retard built into it so i am not worried about starting issues.