Ive got one of those insulated 50 litre Rogue kegs, with the top cut out - handles left on, and a fabricated SS lid which would need some isulation made for. Didnt get around to drilling the hole for the ball valve, but its thin metal so would be easy. Also means you have the option of putting the oulet at the very base (as was my plan).
Ive let it get quite skanky inside, would need a good going over with a scotch brite pad and perhaps some barkeepers friend.
Can take some photos tomorrow. PM if you're interested.