Looks to me like it went lean on topend...and there is too much time between peak TQ and peak HP plus look at the hp curve...
This could be:
inefficient ports
header tubes wrong length/size
collector not right length
throttle stop can affect some engines negatively

IMO, the cam could use a tighter lca. I would try tightening the lash and see what happens.
See if power goes up or down, or doesn't change. Then get back to us.
Post the header tube length's, size, collector length from where the 4 tubes end to the collector opening, and collector size.
You'll also need at least 750lbs. open pressure on that cam with B1's. If not, could be slight valve bounce happening, although the A/F doesn't reflect that...do you know why it went up in the 15's????