5-1 is good. if you have unlimited ammo for any of the magnums, you can run through this one in about 5-7 minutes. you can pick up a jewel beetle, 4 lion hearts (from the lickers) plus $3000 in a safe inside a room for a total of about $16,000-$18,000 per run. there's also a few green herbs and a red herb to pick up. plus, you get 2000 bonus points for getting an "s" ranking on veteran. the u-8 at the end takes less than a minute if you know how to take it out. it gets kinda tedious after a while of playing the same level over and over again, but i've found this to be the most economic way of building up both money and bonus points at the same time.