what is the differents between lt1 cast iron heads and the cast iron heads that came off the caprice police interceptor? is there any?

 

No, they're both junk.

 

First "interceptor" is a FORD thing.

Second the Caprice police package only "performance" upgrades were 3.08s instead of 2.93s and a higher programmed speed limiter. It is just another Caprice. Blues Brothers "super dupper cop car" thinking is NOT applicable.