Here's the intake and Cam Specs:

2 2161 Edelbrock Performer Intake Manifolds - Edelbrock Performer Intake Manifold Chevrolet 396-454 c.i.d TBI V8

2 K11-236-4 COMP CAM :
Advertised Duration 270 int./286 exh.
Advertised Exhaust Duration 286
Advertised Intake Duration 270
Assembly Lubricant Included Yes
Basic Operating RPM Range 1,600-5,800
Brand COMP Cams
Cam Style Hydraulic flat tappet
Computer-Controlled Compatible No
Duration at 050 inch Lift 226 int./236 exh.
Exhaust Duration at 050 inch Lift 236
Exhaust Valve Lash 0.000 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.547 in.
Gaskets Included No
Grind Number CB XM 270H-12
Intake Duration at 050 inch Lift 226
Intake Valve Lash 0.000 in.
Intake Valve Lift with Factory Rocker Arm Ratio 0.544 in.
Lifter Style Hydraulic flat tappet
Lifters Included Yes
Lobe Separation (degrees) 112
Locks Included Yes
Outside Diameter of Outer Spring (in) 1.525 in.
Part Type Camshaft and Lifter Kits
Product Line COMP Cams Xtreme Marine Cam and Lifter Kits
Pushrods Included No
Quantity Sold as a kit.
Retainers Included Yes
Rocker Arms Included No
Timing Chain and Gears Included Yes
Timing Chain Style Double non-roller
Valve Lift with Factory Rocker Arm Ratio 0.544 int./0.547 exh. lift

I can't see where I would have lost power going to a bigger cam set up, I am thinking I'm just missing something simple.

Your cam and intake change will probably only add about 30-40hp and the stock exhaust might not even let it gain that much.
If the carbs were not tweaked for the new combo, then chances are you will gain next to nothing and if they were tweaked wrong, it could cost you power.
Depending on what exhaust you have, you could even have reversion problems at idle.
What is the ignition timing set at? It could be as simple as increasing the amount of timing.

She has a stock manifold with an older Kiekhauffer RIser, I believe the timing is set at factory which if I remember right is 7 degrees.

What ignitions do you have?????
Set the timing so that it is at 34* at full advance.

365hp mag engines with rect port heads came with .510/.510 lift cam. Your peanut port heads can't support that cam. My panther with 330hp engines did 62-64mph. So I'd say you are right where you started, in fact if you were seeing 68mph that is high. Go to rect port heads or a good oval head if you want a pop. I was getting 72-74 with about your cam and edel rect port heads, edel dual plane intake and KE headers.

spinning out will give stern lift and the boat will lean less in turns, spinning in will give bow lift and the boat will lean more in turns