locomotive,
Just to be clear, you're asking about the throttle linkage vs. the clutch/brake cross shaft (lots of discussion on replacing that), right?
The throttle linkage on the L-head is attached to the back of the engine block but the F-head linkage is not. A while back, Shark49's thread addressed this:
https://cj3apage.com/Forum/index.php?topic=5530.msg41447#msg41447Scroll down to his question posted on 19 Nov, 22, 0732am. There you'll find out multiple responses detailing the differences between the two engines.
Back to your question, I like fixing if possible. Sometimes, it makes more sense to replace when wear and tear make that difficult or if hiring out the repair equals a new replacement. I did shop a bit, and noticed a little difference between Walck's version and one offered specifically for an M38 by a military vendor. I don't know if one would be better over the other.