bbc hp estimate
I had a similar (but a stroker) set up, slightly less cam (both lift and duration), 489 inches
(4.25 stroke .030)with a 1050 dominator made 578 hp with a very nice flat torgue curve. It was a roller cam and rect port GM heads, and 10.4 to 1 compression.
good luck !
My guess is 540 ish