The AD724 arrived today - so after the family went to bed I stayed up breadboarding everything.  I think it's all ready to go and I'll start writing the code tomorrow.

What the pic shows is...

Bottom center is Mary Ann's ATmega 162, she'll handle the composite video timings.  She is wired up to receive VCC, GND, and 8MHz CLK from The Island (the main motherboard)  and to send VSYNC signal which The Island uses as an interrupt to tell the Professor (ATmega 162 on The Island) the frame is complete  (This allows the Professor to do maintenance and send then a vsync interrupt to Gilligan [6502]).

Bottom right(ish) is the AD724.  The ATmega 162 is hard wired to send green, blue, red, HSYNC, and VSYNC to the corresponding pins on the AD724. 

Finally, far right is my composite cable for composite NTSC output.

There is also a (hard to see) 3.58MHz clock tied directly to the AD724 for it's FSC clock, it applies a 4x multiplier to it which allows it to stay in sync with the timings required by NTSC composite video. 

My plan is to code up the ATmega to send the correct HSYNC and VSYNC pulses and the red, green, blue colors so color bars are displayed across the screen.  I think getting this correct will be the hardest part of the project.... at least this far.  Wish me luck :-D

A quick side node - the ZIF socket which the ATmega is plugged into is AWESOME.  It works so much better than my previous ones... the downside is it takes up a bit more space, but I'll gladly sacrifice space for ease of use.  It's also much sturdier than the other one, no risk of bent pins.  If anyone else is interested, you can find it at:

https://www.amazon.com/gp/product/B01FDD4M8O/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

I plan on finishing the code this week, I'll post back when I have an update.