Here is what I found on another site. It seems like 1970 was a split year for a big block 727 based off your early and the date below that confirms it.
3410667
A727B early70
Used until April 27, 1970:
1970: Barracuda, Challenger, Charger, Coronet, Fury, Monaco,Newport, Polara, and Satellite w/ 383-2bbl.