The c-6 is going to be very tight. I believe you will need to use a hamer to bend the metal in the tranny hump to get this tranny to fit.
This website may help a little: http://fordifiedracing.homestead.com/bigblockfox.html
Or try this one: http://www.460ford.com/
This some other info i found on another forum site: Weight is about 200# more than a small block if you use iron BB heads. Go with aluminum and knock off around 75-90 lbs. You can use either Hooker, Crites Restoration, or Ford Racing engine mounts. Headers from just about any header manufacturer. C6 transmission will fit with slight modifications to the crossmember (be sure you use a double hump transmission crossmember). An 8.8 rear will live for a while with proper preparations. Depending on how serious of a big block you go with you might want to look into a bolt in 9" rear housing from Currie, Moser, Strange Engineering, or Mark Williams.
An aftermarket tubular crossmember will free up tons of header space and make this swap considerably easier. Our first Thunderbird had a 466" engine with iron heads (unported), a flat tappet hydraulic cam from FRPP, Offy Port-O-Sonic intake, 850 Holley, Hooker 2" headers, C4 transmission with a 3500 converter, 4.11 gears with 28x10.5 tires. Weight came in at 3320 lbs. and the car went 10.50's to 10.70's at 133 mph. No problem.
A stock AOD crossmember requires NO MODS WHATSOEVER, neither does ANY part of the car to make the 460/C6 fit. Just tkae the tranny rubber mount off the AOD and bolt that to the C6 and it'll give you the correct driveshaft angle and it fits perfect.
Fill the converter with 1 QT. of whatever tranny fluid you're using, im using B&M trickshift in my beast, although i do have a manual VB, ratchet shifter and 3000 stall.