The easiest way to tell if it is a cop car engine is to get your nose up close to it and smell it to see if it smells like coffee and doughnuts.
Other than that, if it's a good core worth building, it's worth the 400 bucks.
Yep. I would verify the year and displacement with the casting number and stamps on the pad at the front of the block, if that all matches up and if it's not siezed I think the 400 bucks is a screaming deal for a 440 and 727.
"Police Interceptor" is very vague, most departments buy vehicles optioned out different ways based on a lot of variables. The engine could have come out of a civilian car that the police had a local upfitter modify with lights, siren, push bar, etc. and not done anything with the engine. What work was done to the car could vary greatly, and being 40+ years old you're not likely to be able to find out short of digging into it.
