The stock cable should reach.
You'll have to get a bit creative, the stock bracket can be modified to work. If you can do a little cutting and welding it's not too difficult.
I made mine from a stock throttle cable bracket that I scrounged out of my parts stash, I think it came off a '69 B-body. I bent the bracket over towards the carb to line up the cable with the carb linkage, then I sawed off the lower leg on the bracket and hammered it flat, finally I welded it to the side of the bracket. The bracket is 100% pure Pontiac parts.
To put the bracket at a level where the cable would work I cut down the two threaded mounting standoffs some. After cutting them down enough I ran a 5/16-18 tap down them to get a few more threads, I think I took off about 3/4" from the standoffs. I used a large coarse flat file to cut them down, it didn't take too long but I did get some exercise.
I'm sure your throttle bracket is different than the one I started with, but hopefully this will get the wheels turning and help you to come up with something that will work. If possible get your hands on a spare bracket, from a 2-barrel car or something. You might regret cutting up a good 4-barrel cable bracket if you ever need to go back to stock.
