TTI / 10.5 clutch
See this post for pix of the setup in my 66 Barracuda.
http://www.forabodiesonly.com/mopar/showpost.php?p=162969&postcount=4
I beleive the fork and z bar are both the original 273 pieces. I did not do the original swap over to the 10.5" clutch. I just refined what was already there. The fork is definitely shorter than other forks I've seen that came out of 10.5" clutch bellhousings.
I think you should mock it up and see what will or will not work. Do you have the Doug's headers so you can test fit everything? I've been leaning toward using Spitfires to avoid the hassles, but I hear they don't fit Edelbrock heads which I plan to install in the future.