Clutch Help

[69 C10 LWB]

I just drug a 65 C30 home a few weeks ago and Ive been working on getting the original engine free. Unfortunately Im not getting a warm fuzzy feeling about it. I put a fair amount of torque on it with no luck. There are a bunch of good suggestions on another thread but the more I think about it the less I want to mess with it. I pulled an engine from a truck that has been in the family since 73, when it was new. There is too much history in that truck to just let the engine sit so it will be going in the new truck.

On to the question. Ive been searching online but cant find a good answer. I want to get a clutch kit on order before I pull the 6 next weekend. What is the biggest clutch that will fit in a factory 4spd bellhousing? It looks like 11" is stock and you could get a 12" with a V8. Can anyone confirm this for me?

My 350 has a 12" clutch now and Ill stick with that if it will fit. I need a new clutch because when I put the 4spd in my other truck I used the stock clutch when I first assembled it, just to make sure everything was good, but it chattered really bad so before the engine goes in this truck it NEEDS a new clutch.