MP 557/296 small block cam, advance or straight up

Swapping out my current MP 508/280 solid cam for the MP 557/296 solid. Wondering if I should advance the cam 4 degrees or run it straight up? Provided I have enough piston to valve clearance. Its mostly street driven, only make it to the track a few times a year. Doing bowl and port clean up on my set of X heads as well. It is an old school 340 in my 68 GTS. 727 with 3800 stall, 410 gears, stock replacement TRW pistons, deep oil pain, air gap intake, 750 DP with pro form main body, cheap flow tech headers, 273 rockers for now, FBO ignition with MP adjustable advance dizzy. The old cam ran a best of 12.98 @ 105 with not a lot of tuning and that one ended up 5 degrees advanced. I freshened the motor up in 2000, still has good oil pressure and 180-185 cranking compression. Thanks guys.