Not definitive, but you could check the block casting code to see what it is, as ND said, the last year for the 240 was 74. So a code of D5 and higher would be a 300 block, but could still have a 240 crank from the rebuilder. The dowl or pencil stroke test would still have to be done.
Hmmmmm..... I will try to find castings and maybe I can tell. It's not a big deal I was just curious to know. Most parts interchange between the two....right?
Both were great engines. The warranty for the reman was in the glove box but it didn't say engine size.
It has under dash air that follows the contour of the lower dash... Dealer installed I assume.