Can I beef up my 870 express internals..

[greyeyezz]

to match that of a 870 police? Maybe the carrier dog, sear spring or would it be a waste? BTW my express is 13 yrs old with the metal trigger group.

 

[Virginian]

All the parts on a gun that old should be the same as a Police model, because I think that pre-dates the change over to some MIM parts. Unless you have an extended magazine, you should be good to go.
Almost forgot, you could also convert to the non-jammable bolt package; I think they call it the FBI package. Apparently the local cops are like me, and don't have a problem.