De-tune 360 mag

I have a 94 360 magnum that is fresh.
I built it for my duster, but may put it in my truck 78 W-150 SWB standard cab 435 4-speed 3.55 gear 28" tires
I need to make a truck motor out of what I already have.
As the motor sets right now:
Std bore, Std stroke, KB 107 pistons bottom end balanced, I do not want do anything to the block, crank, rods.
OTB Eldebrock mag heads.
If I put everything right in the compression caculator I have 11.37 static and 10.17 dynaimic.
This is with a Comp XR280HR-10 cam.
.039 head gaskets.
This truck will be used for pulling trailers and heavy loads.
Low usage only about a tank of gas a month.
How can I get the compression down?
Or am I better off building another motor with about 9.1 static and just leaving this one alone.
RPM requirements are 600 rpm to 5000.
Would like to run on pump gas.