Guidance Needed on my 1964 1/2 Conv Mustang

I dont know of any adapter for a 5 to 6 bolt bellhousing, but your not planning to use that old 6 cylinder C4 anyway,,,,right !! The AOD swap is a great one and its probably not painless if you count the money , but it sure leaves you with a nice package. Try this at M&F http://www.mustangandfords.com/techarticles/30194_lentech_automatics_aod_transmission/index.html  

This is a great site also and it gives you some nitty gritty info on the swap and tells you which are the best years to swap.  
http://www.themustangshop.com/c4toaod.cfm