The weakness is the 67 stud idler.
I assume the K-member you have is a V-8 one already?
seems like a lot of money for one part.
if you keep a look out and later found a used K-member somewhat close for $250 or under... you could swap it then. Everything will swap except the $40 idler arm.
I don’t see there being a $620 benefit for what you seem to be planning.
if you were doing a slant 6 to V-8 conversion at same time, I could see that double benefit paying off for $620.
