Matt,
I had an 11" clutch in my 68 (68 C10, 250cid with SM420). The clutch was so heavy that I was hurting my left knee in heavy traffic. I changed it down to the 10" (10.5"?) clutch plate an it's been much easier to drive ever since. If you're not doing alot of heavy hauling or drag racing, the smaller clutch plate may be a good idea. Or talk to a clutch shop about it. The may be able to put softer (weaker) springs on a reman 11" plate for you.
About the tranny, I can swap 'em out all day, but the insides are pretty much greek to me, sorry. But whatever you do, don't try to "bench press" those 4 spds in. I did 3 years ago, and I think the bruses on my chest have finally healed....
