Today's chores were primatily cleaning up, cleaning parts, and doing some close scrutiny. For those who are as clueless as I am on 2.0 and 2.4 liter engines, I'll share what I learned first-hand today.

The heads are nearly identical, except I'm comparing an '89 carborated to a '90 fuel injected. Some interesting facts made themselves obvious.

. While the cam shafts are nearly identical, and could interchange (I would not trust this to work) it's interesting to note the cam lobes are narrower on the 2.4, which has rollers instead of direct rocker arm contact with the cam. A subtle difference is also just behind the cam gear, and it is a "fan" pattern which is more pronounced on the 2.4. I believe it has to do with oil distribution. Lobe-positioning is the same.

. The head gaskets are the same. I measured both heads, and they are the same dimensions.

. As of yet, it appears the cam bearings and rocker arm placement is identical. I do NOT recommend trying to use one cam in the other engine.

. The intake valves are 1/8" larger on the 2.4. Hoping to maybe switch two valves I measured as the first step to that possibility. It won't work.

. The cam gear that the timing belt drives is narrower on the 2.0.

In short, my entire experience tells me I cannot use parts from the 2.0 for my 2.4. Except possibly...and I'll report later...the bolt-down bearings for the cam.
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After the 2.4 cylinder head was cleaned up, I tested the valve seal against the seat by spraying JB Blaster (Liquid Wrench) into the exhaust ports, enough to puddle around the valve seats. The exhaust valve against the cylinder head showed absolutely no leakage.

When this test was done on the intake valves, #1 and #3 leaked. (#2 and 4 didn't). This told me these were likely the valves that had unfriendly contact with the pistons when the timing belt slipped. Close scrutiny showed a very subtle but definitive contact mark on the corrosponding pistons, and a matching contact mark on the valves. A-ha.

So I have ordered two intake valves from (thanks for the recommendation) RockAuto, and will continue cleaning up stuff while waiting for their arrival. Now is a great opportunity to clean the engine compartment and other detail work.

I could read a book on these engines, and I could read this forum for days, but nothing has shown me how these trucks/engines are built, better than hands-on getting into them. There were some fears of the "unknown" aspects, but taking my time, and using common sense, has taught me bunches about my little truck. Not only that, but I can work on it with better confidence in the future.