You know, there are lots of places you can get stuff from, the ones mentioned by Rich_Long and 93_406cobra are both good,
Some others are:
National Parts Depot
The thing is I'm kind of a 'Purist' I guess.
If you put some of this stuff on, Make It Work
(Like when I put on the side scoops I bought the scoops from Maier Racing along with vent tube kits which direct the air onto the rear disks.
The Calif. Special trip might be nice, but as KULTULZ noted the Deck Lid and extensions are necessary 'majors'.
I think all the parts are available though.
Thats the The_Good_News
The bad news is there are a lot of details and they'll end up costing a bunch.
Of course if you just want to dress it up a little, you can do as '77 Regal suggests.
You're still looking at some detail though. (Getting parts that fit, hardware, installation, etc)
So I guess the point is: Be sure to plan your project out ahead of time. Locate all the parts, figure out your budget, etc.
Your car sounds pretty nice, the 351 Windsor in mine came out of a '69 fastback.
If you want to make it go a little better there are Lots
of not-too-expensive things you can do.
I can tell you putting the edelbrock heads on mine had the biggest effect!
You can pick up a set used if you shop around.
Good Luck with your project.