YellowMach69 I think you made the right choice and most of us on these forums would have done the same. I too love the old Mustangs, I still want to find a 68 GT and build it, but I have an 05 on order.
Its easy for all of us to say"you should have kept it and then bought the 05 also" , but reality is most of us dont have that kind of money to have two cars, a hobby car and a daily driver.
I love the 69's also and would love to have a Mach 1 ,that could have been a nice car but it looks like it still needed a lot of money and work to be right.I'd say you got a good price for basicly a project car. Now if it was already restored complete or had some real colector potential like a 428CJ engine, or an "R" code or all matching numbers or something like that, well then it might have been different. But if you look on line at Auto trader or colector car sites, a basic 69 Mach 1, with 351, there are still quite a few of them available, and in the rough they dont bring much more than what you sold yours for.
And the beauty of the 05's ,besides just their awsome looks, power, quality and performance, is that there will be plenty of after market parts to make the 05 look similar to any of the older classic Mustangs like the Mach 1's. Now I havnt seen the side scoop up on the quarter panel like the 69 Mach 1's but I have seen the shaker hood, the front air dam, the 05 comes with a wing thats is almost an exact copy of the 69 Mach 1 wing, the rear window slats, the honeycomb rear treatment between the taillights, the Magnum rims, and I'm sure theres more stuff I have missed.
Myself I'm looking to add some parts to my 05 that I love from my favorite Mustang of all , the 68 Shelby's, like the rear ductail spoiler, the side scoops, the front end air dam like the Cervini Elenore , and maybe a small hood scoop like the Shlebys' had.