[NINFan]

Hi-

Need some advice. My son has a '99 4X4 that we bought used and later learned that the first owner didn't really take very good care of it. A while ago, he asked me "dad, what does it mean when the 'check gauges' light comes on?" Turns out the oil press was low. I checked the sender, and it's fine. Now it's developed a valve tap. I naively bought an oil pan gasket, thinking I'd just replace the oil pump. Got under the car and realized it's not so simple on a 4X4. So I figure I've got 3 choices:

1)Do nothing and let it die a slow, painful death.
2)Adjust the valves and hope that takes care of the valve tap, just drive it with low oil press until it dies a slow, painful death.
3)Bite the bullet, pull the tranny and transfer case, replace the oil pump and let it live a long, happy life.

Option 1 is really not great.
For 2, I dug around a bit on the web and it seems that everyone is talking about adjusting lash with a feeler gauge. Back in the day, we used to adjust the valves with the engine running, valve covers off, just back off the nut on each rocker one by one until it taps, then turn it back down until it just stops tapping. Does that not work anymore? (I was a mechanic for a while, but haven't done major engine work in many years, so I'm a bit out of touch.) Also, I once made the mistake of starting the car with the air cleaner disconnected and had to take it to a shop to get rid of the dash light. How can I avoid that?

For 3, again, back in the day, in similar situations we had been known to fill the oil pan with solvent (like safe t kleen) and crank the engine (with the coil wire disconnected so it wouldn't start) and run that stuff through the pump and engine, then fill it with new oil, run it a while, change the oil again and it would clean out all the sludge that was in the screen of the pickup on the pump, which is what I suspect is happening here. Used to work like a charm, but I'm not sure I want to try that again. So if I don't do that, how bad is it to get to the oil pump? Can I get the transfer case and tranny out of the way enough to do it with the car on the floor? (I've got jack stands and a floor jack.)

Thanks in advance for your advice.
btw, I searched the forums and couldn't find a similar thread, so sorry if this has already been answered elsewhere.