The dual sump pan was used in car ch***is(primarily the fox platform) from about '78/79 to '95. Just at a glance I see that your timing cover doesnt have a mechanical fuel pump provision and the pan has an oil level sending unit bung so you likely have an engine manufactured/originally installed in something post 1986, although there are a few exceptions.
87-88 351W powered Crown Vic used a similar oil pan.... I have one in my 91 pony..... Yours is probably a 302....
302 and 351W are same length. Deck is taller, intake wider. Need to see the intake to tell. 302 HO carb motors used a 351W 4bbl camshaft, that is the reason some 302's had the 351 firing order.
If the top of the deck is even with the top of the water pump right in front of the head it's a 302/5.0. If there is about an inch between the top of the water pump and the deck it's a 351W/5.8. Looks too short, it's either a 302/5.0 or worse a 255. Look like a 302/5.0 from the outside. SPark