Oil filter VS oil pressure?

Hi!

I have a mildly tuned 318 in my car, an old one which has probably never been rebuildt.

Its probably well worn, something I suspect from how the oil pressure behaves.

I run 20-50 oil, and when starting from cold, the oil pressure is great with arround 25 psi on idle and up to 70 with some throttle.

When the engine gets warm, this deteriorates noticeably, and at idle, the pressure gauge needle is barely above zero, and if the engine stumbles a bit, the oil lamp blinks.

As I'm contemplating a future HEMI III upgrade, I just want the engine to last a couple of seasons more without sinking money in to it.

Now to my point:

I am currently running a tall AC delco filter for no other reason that they hapened to have it at a nearby AC delco parts store.

Could changing to a different brand filter improve the oil-pressure somewhat, or is it really all the same?

Br,