I believe Robert Raney has a C6 in his BBF Maverick. I have a C4 with a Performance Automatic hardened input shaft, Transgo shift kit, and 3500 converter with otherwise carefully chosen stock Ford parts behind my 460. Cleaver
With some well placed work and some good parts the C4 is good to 600 HP and with some dedicated machine work and close tollerance work you can make one live a long and productive life behind 1000 HP and more.