slash, I hope others chime in with their opinions. Using a clutch with the 212 will be fine. You will not notice much difference in 11,12, or 13t sockets, but 11t will climb the best, but you will just have to get used to managing your throttle twisting. A clutch can be grabby, and it can also get hot on lots of hills, but it will definitely pull you up them. I prefer the torque converter because it delivers power smoothly and they are load sensing - i.e not "grabby".
A clutch-on-a-hill scenario:
Lets say your on a steep bumpy hill (not a typical suburban street), you are slowly making your way up but the slipping action of the clutch isn't moving you over some bumps (and is probably getting hot), so you carefully twist until you get the power you need. However, this little bit of power may come as a jerk with a clutch and if the hill is steep enough, may flip you off the back. With the TC, none of this is relevant - it just goes uphill while you sip a cocktail and/or cut diamonds.
As far as room for an adapter plate, you wont have room for the stock muffler, but some aftermarket mufflers will work.