1967 was a transition year. The valve angle changed from 20 to 14 degrees on only some of the 1967 heads, the large-valve performance-oriented heads such as the 670 and 061 had 14 degree valve angle and the longer pushrods (9.145").
Your 143 heads are the older-style 20 degree heads and should take shorter 8.715" pushrods.
You will need the longer 9.145" pushrods to use the #46 heads.
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