It has the 67' 273 valve covers, so someone tried to make it look like a 273. First thing I would do before driving it is, change the thermostat housing. Those chrome ones always leak.
Not a bad thing. 87 is probably a roller cam engine with the famous 302 casting heads. Good chance of it unless it's been messed with. A 318 4 barrel with headers is a swap that many 273 guys strive for.