It's an 80--well, it came with a 301--you know, that thing with the same exterior dimensions as the 400/455 but 2/3 the displacement and about 130hp.
The 455 Pontiac has a 4.15" bore and a 4.21" stroke. The 454 Chevy has a 4.25" bore and 4.00" stroke. I wouldn't call the 454 a short stroke. Here's the pecking order amongst the biggest of the old big-blocks in stroke: Cadillac 500- 4.30"; Olds 455- 4.25"; Pontiac 455- 4.21"; Chevy 454- 4.00"; Buick 455- 3.90"; Ford 460- 3.85"; Mopar 440- 3.75".