How can I tell a 265 Power pack V8 from standard 265 V8 Engine

The Power Pack option in 1955 had the same heads as the standard 2bbl 265. The peaked “triangle” power pack heads didn’t appear until 1957. A 55 Chevy with original 265 power pack is uncommon but not rare enough to be 100k (depending on model body style and caliber of restoration) and equally hard to prove since there isn’t much identification in the numbers. Date coding all parts would be a clue but that also leaves chance of change. The only way to really know is original bill of sale with the options listed. I own a 55 with original 265 Power Pack which I race in stock class. Has Corvette style solid lifters and same small port heads as the standard 265 of that year.