Yet another 292 Identification Help Request

[Portland68]

Picked up a 68 K2500 yesterday that had the V6 swapped out for an L6 and I’m having trouble identifying whether it is a 63 or 73 block.

Casting number is 3851659 (63-76 292)
The number near the dipstick is CON2 ?243, the ? Could be an I but that doesn’t really matter, 24 should indicate the 24th day of whatever month, 1963 or 1973.

The tricky part is the engine code is F1029PG and I can’t find that suffix anywhere and the by the numbers books don’t give any love to the inline sixes.

Any help would be appreciated! Picture of the latest rig I saved from the scrapper included.