I am also unable to find a schematic for the ttl to rs232 interface. I know it will consist of a few caps a 7805 VR and a max232 or max233 (eliminate the caps) possible a diode or 2, but as far as a layout or schematic i am lost
Typically you need the MAX232CPE :
All you need is five 1uF capacitors.
100mA voltage regulator :
0.33uF and 0.01uF on the input and output side of the regulator.
Up to you if you wanna use the MAX233 without needing external capacitors. They cost more and can be hard to find in a local shop.
The OnCore units are pretty solid. I've got an M12 and love it.
Why not run an APRS app on your computer? There's one that integrates with StreetAtlas (APRS+SA), or if you're using Linux there's Xastir (www.xastir.org).