Pull the heads off and measure the bore. Doesn’t really matter, it was originally a 307.
Yes 307 and 327 are both 3.25” stroke.
The factory SBC and SBC design capacities go something like this, in roughly chronological order:
265ci. 3.75” bore, 3” stroke.
283ci. 3.875” bore, 3” stroke.
327ci. 4” bore, 3.25” stroke.
377ci. 4” bore, 3.75” stroke.
350ci. 4” bore, 3.48” stroke.
302ci. 4” bore, 3” stroke.
307ci. 3.875” bore, 3.25” stroke.
400ci. 4.125” bore, 3.75” stroke.
262ci. 3 2/3” bore, 3.1” stroke.
305ci. 3.736” bore, 3.48” stroke.
267ci. 3.5” bore, 3.48” stroke.
Edited by user Thursday, 22 October 2020 7:03:40 PM(UTC)
| Reason: Not specified