I haven't used either one of these devices, but sometimes I just like to see what I can dig up. Here's what I found. There is enough information in the manuals on these units to do the job, providing you have all the stuff that came in the box with them. The radio came with a GPS/External Speaker connector/cable with an 8 pin connector and bare wires at the end. Got it?
The GPS came with a PWR/DATA cable which I think you have because that's how the GPS gets power.
Your GPS speaks NMEA 2000, which is good, but has only one bidirectional com port for NMEA 0183, which is what the radio speaks. Com-1 uses the yellow wire to transmit, the orange wire to receive, and the shield wire for signal ground. Your unit does not use the blue wire.
You made a very good choice of radios, this one is crammed with features, but isn't any harder to learn that another one as far as DSC goes.
You need to make three connections:
The data grounds (three 'wires') are all connected together; The shield from the GPS connects to radio's yellow and orange wires.
The GPS's Orange wire connects to the radio's green wire, and the GPS's yellow wire connects to the radio's white wire. That's all you need to do for DSC except:
[This is the hard part] Go to
www.boatus.com and register for an mmsi number. Its just like a telephone number for your boat. Then [gasp] read the DSC stuff in you radio manual. It too is just like a telephone, including conference calls, direct dialing, and 911!
Then read the GPS manual (which I found on line at
http://www.lowrance.com/Downloads/Manuals) to see how to tell it there's a DSC radio connected to it.
I am an idiot...please give me some helpful advice 
