in my opinion you wont make those numbers in the current configuation. Your A/F numbers show your not lean and while timing advances will help quite a bit, that 470 peak at only 4,200 is not gonna get you there. I'd like to see a dyno curve of your run.
420hp@5800 shows your torque curve is falling off alot on the top end. That's not a charecteristic normally seen with a 4" arm. I'm wondering if the cylinder head/cam combo is working for you. Also, if your only using 1 5/8" headers on the dyno, that's not helping the situation.
About what i expected. Don't be too dissapointed, even if you just leave it alone those are some stout numbers for a street car. And as moper say's, on pump swill, not bad at all.
P.S. That's 460hp and 490lbs.ft more then i have right now.....lol.
