Presuming the 4.38" blade length (K390 model) doesn't violate any local ordinances or state law, it's really up to you and how it fits your carry desires. The standard Police model has a 4.125" blade length.
I have an early production all-stainless Police model from the mid/late 90's, when they made some fully serrated versions engraved with Navy Seal Team logos. I picked it up as an oddity that struck my fancy. Personally, it's always been a bit too long for my pocket carry desires.
However, the current generation of the Police has the carry clip positioned differently, and for 4-way carry clip attachment, versus the 1-way Tip Down carry of my old one. Depending on the carry orientation chosen, that might extend the body of the handle even deeper into the pocket than my old one. Your call.
Here are a couple pics I just took of my old Police, a new Buck 110 Slim and a Spyderco Endela (Thin Blue Line model). The deep carry clip of the 110 makes it stick a little lower into the pocket, but the Police sticks up higher, and the top edge can poke into my hip above the belt line when seated. Annoying.
The Endela is the most comfortable of all, but the blade is the shortest, being 3.41" versus Buck's 3.75" and the Police K390 model's 4.38"
FWIW, I also have a Benchmade Contego, with a 3.98" CPM M4 blade. Even though it's blade length is a bit shorter than my Police model, and the handle is 0.34" shorter than the K390 Police, or similar to the standard Police, it's deep carry clip positions it differently and makes it feel longer in the pocket.
Gotta find what's comfortable and handy for you.

I rather like the 110 and Endela, which is why I don't own a newer version of the Police or the Endura.
BTW, you realize the K390 steel needs to basically be treated with the same care (to prevent rust) as carbon steel, right? I picked up a Spyderedge Delica K390, because I liked the K3990 steel, and the handle color Spyderco uses for it,
and the Delica is pretty much my favorite and all-around handiest blade & handle length for EDC chores. I own several of them.
Suit yourself and enjoy whatever you choose.