360 Magnum building on an existing bottom end

This is the only Comp I see close to what you mention
PLYMOUTH COMP Cams 20-244-4 COMP Cams Magnum Hydraulic Camshafts | Summit Racing
IIRC, this is the cam listed on that page. Regardless….
Some of the other newer cam options have higher lifts which I would look at with fully ported heads. If the cam doesn’t lift the valves well into the heads best and highest flow area, look at 1.6 rockers, which the Magnum head has but I’d look at better than stock for this.
Personally I’d take a peek at this and do some math on the valve lift w/1.6 rockers and see if it fits.
PLYMOUTH COMP Cams 20-229-4 COMP Cams Xtreme Energy Hi-Lift Camshafts | Summit Racing
Lift (.564) divided by stock rocker ratio (1.5, which the advertised lift is based on) then multiply by new rocker ratio (1.6) will equal the new lift of .6016

The new ratio (or stock ratio in the Magnums case) will add a minor intensity to the cam and really help open the valves up quicker and higher into the cylinder heads best flow area of its curve. It’s worth a little power, for sure.