First I must ask, why bother with one of those. Do you have thermopile sensors or a imu sensor board. I flew one of these a back in those days. Had 3 axis thermopile and GPS and 2 way telemetry. I may still have a copy of the firmware that I modified.
I still have the hardware and a custom ground station based on the 328.
Thanks Chris! I carefully reviewed both links but unfortunately the are all for the Mega 1280/2560. There is no version there that will work with the Atmega 328.
I found and old manual fort this board and says that the code was an ArduPilot 2.3 version. Does someone have copy or link to that source code?