These International sixes have a reputation for being "cold-natured" and needing more warm-up time that competitive makes. True or not, that's the reputation they have. Now, I'm not going to bore you with a talk about how these engines are more efficient when the engine is warm enough for proper fuel atomization; you already know that.
Obviously, there's no place on the internet to check availability of the correct parts for these old trucks. But occasionally there's a "work-around" for that...if you remember that the C-221 ag engine was based on the SD-220 and BD-220 truck engine.
So I went to the online parts catalog at
http://www.caseih.com and looked up the corresponding parts for a Farmall 460 tractor. Then I compared those part numbers with the corresponding parts in the MT-63 truck parts catalog for the L-110/L-120. The only part numbers that are different between the two engines are the plate [371098 R1 on the 460, 70212 R1 on the SD-220] and and the weight on the pivot shaft [85699 R1 on the 460, 82960 R1 on the SD-220].
So what does all this mean? Depends on how committed you are to replacing the parts. From the tone of your post, it sounds like you're not really committed to it, but then I may be reading your thoughts wrong. Bottom line is, it's your truck, so it's up to you to decide whether you want it or not. I've seen these trucks run with these heat control valves inoperative, so apparently they will run with or without it. You have to decide what's important to you, and go from there.
The bimetallic spring is 82958 R2; the shaft is 82958R1; the bushing on each end of the shaft is 69443 R1, and it takes 2 of them. The plate for the truck engine is 70212 R1, and the weight is 82960 R1.
My posts contain my own opinions...your mileage may vary, void where prohibited, objects in the mirror may be closer than they appear, and alcohol may intensify any side effects.