We dyno'd a newly done 440 that was in my Belvedere & it made 428 hp & 468 torque without a tuned carb & adjusting. I expect it to make 450 HP at this weekend's dyno session & then its up for sale.
67 HP block, Mopar forged crank, SRP pistons, Eagle rods, stock 906 heads w/ 1.7 Source roller rockers & big purple shaft hyd cam,
RPM dual plane & Holley carb. I was amazed it made that HP with unported 906 heads & no tune. All we did was check everything out, break in the cam, put on a shop carb & go. Build sounds close to yours & we're at almost 5,000 ft elevation, so I would think you're close to these numbers.