On another thread ( http://www.californiaspecial.com/forums/showthread.php?p=51915#post51915 ) The issue of seats and legroom/headroom was initially discussed ... I did a little research and here's what I found:

http://www.mustangsplus.com/tech/seat/index.html

http://www.mustangmonthly.com/howto/38039/index.html

These links deal with the pan, which can get labor intensive, but it maybe the best overall solution.
Other solutions could be to change to a different lower seat, or create an adapter to allow you to slide your seat further back ...

http://forums.vintage-mustang.com/showtopic.php?tid/1443892/post/1547666/hl/legroom/fromsearch/1/#1547666

Also, some have swapped out the original steering wheel for a smaller one to make it a little easier for "wheel-to-thigh-clearance" ...

... and here's another link that does similar solutions:

http://www.geocities.com/troop851cali/project_legroom_top.html

Ford actually had a service tech bulletin about moving the seat back 1" or 2" if people complained. Don't remember where i saw that now.

I have the word document referenced in the VMF forum. It's a big file though as he said - too big to post here. It's a 6mb file. PM me with your email if you want it.

I found the Ford service info on the seat extension...