For a pump gas, muffler acceptable combo, I would stay away from the MP 620 cam. It likes lots of CR and its tight LSA (106) isn't muffler friendly.

And IMO, a 500+ CID engine, especially with moderate heads, needs some LSA to go along with the desired duration. Maybe 109-112 LSA and 260-280º at 0.050"

1993 Daytona, 5.50 at 130mph (1/8) 1.19 sixty ft (PG). Link to 572 B1 - Part 1