Do I Need a New Oil Pump?

[pacotaco345]

I'm getting ready to buy a timing kit for my car.. I've had timing chain rattle since I put this motor in it over Christmas break (its a 95 ka that I swapped into my 91).. I've put a new upper tensioner in it, removed the guides, and it still makes a ton of noise. I'm tired of having to shut off my car in drive thru's just so people can take my order, the motor is great aside from that one issue, it leaks down at 12% across the board, and it has above 155 psi compression everywhere. When I start the car though the oil light stays on for about 30 seconds unless I rev it some. The only thing keeping me from replacing the oil pump is the cost, I figured I might as well replace it since I'm gonna have it off anyways but do I really need it?