mine is a 1972- K5? the carbs are 723 A's. Would the 150's be too rich for this motor? I guess 4 into 1 bought these kits, put their name on the bowl gasket and added a 150 jet. $8 dollars more is no big deal right, both free shipping but the 4 into 1 comes from San Fran rather than Taiwan. I heard someone on here state what quality stuff 4 into 1 had, I will probably go with their kit to get the other jet and get it shipped quicker. Oh yea when did the 450's go to 5 speeds (when the 150 jets were put in 723 B's) I think.