I've got the same style engine in my truck.
Here's what I did, put a grommet and the PCV valve in the hole in the back of the block and will run the hose to the back of the Carb with a hose barb. Then use a breather cap on the fill tube. The original 2bbl carb has a pipe thread where the original PCV valve screwed in, 1/8"? I think?
Grommet: Dorman/Help #42323
PCV Valve: Standard V158
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Sorry about the enormous pictures. Just really trying to get my point across, I guess.
Hope this helps.