My guess depending on minor items could be up tp 525 hp. My old 440 was a close build.
It was a .030 over 440 with a stock bottom end and KB pistons. I use 906 heads I ported and the KB pistons were the quench dome pistons as I had 10.0 comp and about .046 quench. MP .557 cam with the Holley Street Dominator intake and the 850 DP. Hedman 1-3/4 headers and 3" exh. Never dynoed but ran a best of 11.49 @ 116 in my 3700 lb 63 Sport Fury which figures to about 500 flywheel hp give or take a few. Sounds like a decent fun build. Good luck , Ron