I was gonna give my car a tune up today only to find out that 3 of my plugs had oil on them. the other 3 were all black and sooty. Which means that its running too rich right? And the other 3 with oil means that my piston rings are worn right?

If so, which would be better to do:

get the old l24 engine fixed? or buy a newer l28? I would rather get the l24 fixed but if the cost is equal to getting an l28, might as well upgrade then.

.....I understand the temptation in upgrading to an L28. But, why not consider sticking with the L24? More and more 240's are no longer equipped with the standard L24. It's not a bad thing as there are advantages to this. However, I think it would be cool to preserve that original sort of aesthetic.....mechanically speaking that is. Then again, $$$ talks.

Which 3 plugs? If the problem plugs are the front 3 or the back 3 it could be carb-related. It's possible that the oil is actually unburned fuel.

Do a compression test. That will give you a better idea of the condition of your engine than just checking the plugs.

It's always nice to be able to say your car is 100% stock knowing this to be true in the back of your mind. If you do opt for the L-28 be sure to keep the L24 just in case you want to revert. I had an L-28 w/ SU's as a "temporary" five year motor. (It only cost $125.00!!) It pulled great but top end performance suffered due to poor breathing from the SU's. Looked like someone else bored my SU's a tad too.

It's also nice to have a spare motor, radiator, etc, etc.

yeah, I'd do a compression test then go from there. I THOUGHT my car was burning oil because it was smoking (and it looked like oil smoke) and when i pulled the plugs they were a nasty black, well I also found out my car was running stupidly rich. I also thought that my plugs were wet with oil, but once i fixed the stupidly rich problem, no smoke, no wet plugs.

i cleaned the spark plugs and then leaned out the carbs a little bit. then i let it run for a bit and checked the plugs. the plugs where still a tad sooty but leaning it out did help. BUT...now when i drive the car, it really struggles uphill and i can't rev pas 2500 rpm without it gurgling and coughing. still haven't got a compression test yet. is it easy to do? if so, i'll just buy a kit and do it myself.

When you started this thread you mentioned that you were about to give the car a tune up. That is still a good place to start. Your timing may be off or you might need new plugs, cap, rotor, points, etc. A compression test is easy to do if you have the tool. Here's an example available at Sears:

http://www.sears.com/shc/s/p_10153_12605_00947089000P