I put one in my '65 coupe and it fit fine- no floor mods. I will admit while I like the extra gear, I hate the shift pattern. If I were to do it again, I'd have it rebuilt with a different valve body, or go an entirely different route. It shifts so quick on the low end that it's not enjoyable- so much that I'm considering going back to the C4 and 3.50's (3:90's now).
About to do this on the wife's 65 coupe. I bought (have not installed) the Hurst cross member. It's beefy. Looks like it tucks up a bit better than the others I've seen, but again, it is not on the car yet. I have an SPT-R valve body in the AOD (also not installed, the transmission not the VB) so it will hold in 1st if you manual shift. Eliminates the "1-D-1" shuffle according to the lit. Has an OD lockout as well, so you can drive it 'old school.' I am only adding OD for the long trips. Also changing to a 3.55 rear. Seems like the best compromise for her car. She doesn't want to burn rubber. I would like it to be a little quicker off the line than the stock 3.00.
There is no sheet metal change required to the tunnel.
You will likely need to reroute the exhaust as the AOD is much wider than a C4. It is problematic, especially on a convertible with the extra bracing under the floor pan...and will generally end up being pretty low.
I believe you will end up needing to shorten your driveshaft. I know I had to to install and AODE-4R70W.
You will need some sort of mount/hookup for the TV cable in the engine bay.
I went with the 4R70W as it included all of the beef-ups that the weaker AOD ever got, fixed the goofy shift pattern, is easier to find in unmolested condition used (Junkyard 3.8 V6 mustangs or 302 explorers are the common donor)...and it doesn't need a TV cable. It does require a Transmission Controller....but when I did mine, not being able to find any good-used AOD's....I saved enough money on transmission (rebuilt AOD vs Junkyard 4R70W) that it was cheaper to do the more modern transmisison.
Might not have to shorten driveshaft. Depends on output shaft housing. Apparently there was a long one, or there is confusion about a long tail housing. Mine is from a truck originally and has an overall length that is only 1/2 inch longer than a C4. I do not expect to have to modify anything here.
I don't know that there is a kit, but basically what you need is: an adapter mount (available from catalog sources), an adjustable shift linkage, a lokar TV cable kit, and a neutral-safety switch pigtail to splice into the factory wiring. Not a long list of items. Do be aware that a stock H/Y pipe will not fit around the wider case, so you will also have to do some exhaust modifications for the AOD to work.
I've donned my flame suit, but I still, for the life of me, can't see why anyone would want to remove one of the best automatic transmissions ever made (from the standpoint of durability, weight and efficiency) for one of the worst....