If you've only got 1/2 a mile cruising on it like that and it's only at 2500-3000, if it is rod knock it's probably not that bad. Sounds more like a chain slap or piston slap to me. The only rod knocking I've heard was pretty obvious at all rpms under vacuum, including bliping the throttle to 1500 in neutral from idle.

You're going to have the engine mostly apart to do the pump (have to pull the head and pans), so might as well pop a few rod caps and take a peek. If the crank isn't scored, just slap some grade 0's in there and call it a day.