Help identifying modifications made by previous owner

[Truchero]

Hi! I’m in the process of reconditioning a Pearson Renegade. The motor did not work when I got it. I rebuilt the carburetor and now it starts without any hesitation. I’m on the hard and I’ve limited running the motor to a single 5 gal bucket. Anyhow, the engine appears to have gone through various modifications. Could someone help me figure out what is what?

(Please forgive how dirty the engine looks, I’ve been fiberglassing and sanding the boat for three months and have just got to working on the engine)

1) the thermostat appears to have been removed and there is a bypass valve, am I correct? How would I use it?

2) there is an external fuel pump that runs when I turn the ignition. There appears to be a switch on the back of the engine. Presumably to turn off the pump in case the carbs overflow or something, correct??

3) I changed the coolant and looked at the anode, it looked fine. The heat exchanger was warm when I ran it, so I think it’s working. Does it look like it was properly installed.

4) any other mods that you see?

Thank you!!