Cam & head upgrade 360 mag

This is what I did to my 2003 360 300 HP Magnum Crate:

360 Magnum roller, 9.3:1, OEM magnum heads milled .010, .028 head gasket, stock valves, MP crate motor springs, ported by me at home.
Knockoff airgap, demon 650 DP, Lunati roller steel core custom grind 234/236 .495/.475 lift. 108 LSA/106 ICL
999 low gear set, TF2 shift kit Lockup circuit disabled, Turbo Action 10" 3200-3400, 3.91 SG, 27in MT drag radial, Mancini SS springs, 8.75 axle moved back .75", battery in trunk.

Wallace Racing HP calc for 11.946 ET 3360 lb car
HP computed from your vehicle ET is 350.59 rear wheel HP and 389.55 flywheel HP.
HP computed from your vehicle MPH is 337.14 rear wheel HP and 374.60 flywheel HP.
Motor has over 400 torque and pulls the full 1/4, nose drops only when you lift.
I'm still tweaking to find more top end power. I suspect more gear and converter would do it, but I drive 50 miles to run the car.

OEM Magnum heads are very good and I assume yours are low mileage. They respond well to blow cleanup and port match. You need to be careful with piston to valve clearance with the OEM pistons, there are no valve reliefs. My .010 mill of heads, swap to thinner head gasket, 234@050 dur, and .495 intake lift resulted in .050 P to V clearance. My exhaust was .100 so no problem there.

You don't need to drop a lot of $$$ in your motor. I'm using the same lifters, pushrods, rocker, and valve springs that came with the crate motor. IMO a good Cam and port of what you have will work. Call Justin at Lunati Cams with your combo. The guy is good and won't BS you.