Thanks for the help guys. I think I'm going with the 75 model because the frame and motor have the same vin's and it's black, can't go wrong with black 
Mine too has only 9 digits and the motor matches the frame steering head. When I had mine powdercoated, I had them mask off the vin area and then we clear coated over numbers so they could be read. The black powdercoating would have filled most of the numbers/letters.
Here is a picture of my '76 FLH taken about 7 years ago. It was a blue AMF paint scheme. I took it all down to the frame and powdercoated everything that was black, except for the tins that I had painted the classic black and gold.
The prices for Shovelheads has dropped a LOT... Back when I wasn't too interested in selling mine, I might have been able to squeeze out $10k to $12k for this beauty. But now I would be lucky to get $7k to $8k for it. I've seen some very nice all original FLH's with all the bags, pogo stick seat etc offered at less than $8k.
Do you have pictures of the two you're looking at? What are they asking for them if I might ask?
Good luck with your purchase. A good Shovelhead can be a blast to ride. Since I bought my '08 SERK back in November of 2007, I've not ridden my Shovel more than a couple times. But before when I would ride, my wife and I would stop at the local biker wateringhole and many of the newbies would compliment me on my new bike. I had to let them know it was over 30 years old. Most of the people really dug the old bike.