What should I do about the engine?, I've got a few choices, need your input Options

[Type 47]

So, finally after 10 years we are getting it put back together. Things are progressing OK, many issues but things are moving forward to the point where I need to think about what to do when it comes time to put in the engine.

I little history: 75' 2.0 with 62k miles. the PO had replaced the FI with weber carbs but had put the FI in a box. The strategy for the rebuild is to get the car from parts in a box to functioning. The debate about FI vs. Carbs will wait for another time (we did put both SS fuel lines in the tunnel). So we are putting the Webers back on initially.

Here is my engine question: I have 3 engines. Behind door #1 is the 62k engine running fine when car was disassembled. A 75' 2.0. The issues with this, is the emissions crap that was done to the heads. When I realize the emissions crap, I was like WTF what are these tubes?? this engine has no heat exchangers but some kind of exhaust system that eliminate the heat for the HVAC system. Has full engine tin, alt, etc.

Behind door#2 is a late 73' 2.0 core with no tin.

behind door#3 is 74' 1.8 that has been apparently upgraded with a big bore kit. This engine has SS heat exchangers.

So what do I do????

1. just spray WD-40 in the spark plug hole of the original and cross my fingers?
2. rebuild the 73' and put the 2L sheet metal from the original engine on it (it would fit right??)?
3. I can't see a scenario where the 1.8 works. Maybe trade heat exchangers for one to fit on the 2.0s, rebuild and sell it.
4. or put the heads from the 73' on the original engine?

My tech (son) is really getting tired of putting on seals and is jonesing to rip into redoing an engine.

please advise