-The car's a 1990 Honda Accord EXR 4DR.
-It was in a accident with left driver side body damage.

The problem is now that the oil cap leaked, and so oil seaped into the spark plug ports (so the car wont start).

What kind of work is needed to repair this?
Is it going to be cheaper than putting a new engine into the car?
(how much would a engine for 90 accord exr be?)

,Thanks

The oil in the spark plug tubes probably came fom the O rings that seal the valve cover to the engine. You can buy a gasket kit from most aftermarket stores for about $30.00. It will include the cover gasket, 4 sparkplug tube seals, 2 valve cover bolt seals and 4 O rings that go under the cam holders to seal the bottom of the sparkplug tubes. Changing everything except for the O rings that go under the cam holders is easy. Soak up the oil in the tubes with a rag or paper towel and solvent before removing the spark plugs. Then really clean the tubes with a rag and solvent to get the oil out. While you are at it, you might as well replace the spark plugs. If the oil cap leaked it would blow oil all over the engine compartment. If the cap leaks, you can buy a O ring/gasket or a new cap from the dealer for about $7.00

Yah there was oil splattered around the engine compartment

Also check the PCV. If it is clogged, it can force oil out of even good gaskets.

Well we know that the oil didnt come from the bottom-up, it was the oil cap thats leaking and oil went in from the top of the engine. do I still have to replace the O rings? what kind of solvent do I use?

I'd just mop 'em out with a cloth, replace the plug wires, and see what happens.

I've seen cars come in the shop running with oil-filled plug wells....I don't see why that would keep it from starting...

What kind of cleaner should I use to clean out the spark plug chambers?