Hate to chime in on the bad news but there is no way your making that kind of power with that build except on dyno's in A _ _ _ _ _ _ S.
I run 11:1 ported Ed. heads, big cam, Victor Single plane, Jessel Rockers, and balanced to true race standards. On a REAL dyno my logged 543 hp & 500 TQ. That's the reality. If you want big numbers with FE's it requires lots of $$$$ and compression. Enjoy the 425-450 you'll end up with unless you go to A _ _ _ _ _ _ S and then enjoy 650 hp.:LOL
THE OTHER PROBLEM is Webers like compression (real compression ideally) and don't like split duration cams. I hope your builder knows what he's doing. I also have a 428 w/ IDA's and know a little about the Webers as a result. Lastly, FE's (at least 427's) solid lifter motors run lifters with a 1.76 ratio - 1.72 in your build - I don't know. Best of luck!