Request help with cooling system on a 94 Buick Regal

I was hoping that some one here might be able to help.
My parents have a '94 Buick Regal 3.1 L. The freeze plug corroded through. So, my father was going to pull the freeze plug and replace
it. The first problem was that since the engine is mounted sideways in this model vehicle and the plug that corroded through was towards the firewall of the vehicle. Not having the knowledge to pull the engine he released the motor mounts and pulled the engine forward. He was able to get some access to the plug; however, it would not pull out. In his frustration to pull the freeze plug, he just kept making the hole larger and larger. Anyway he was not able to get the plug out, but left a rather large hole instead. Still not thinking that he could pull the engine, he used some JB Weld to form a type of plug and placed it in the middle of the hole in the freeze plug. Of course the putty also filled into the block. He allowed it to set for the night. After the weld set, he filled the radiator and block with coolant and water. The temp gauge then rose to about 250 degrees after approximately miles driving distance and he noted that the water pump was leaking and the radiator fan would not turn on. He replaced the pump and the fan temp sensor (or whatever you call it). The senor still would not engage the fan, but when he jumps the fan connection and bypasses the senor the fans work without difficulty. The Temp gauge would still rise rapidly and it seemed to overheat. We then replaced the radiator with the thought that there was a restriction of water flow through the radiator (due to his use of radiator stop leak). Still no success. It seems that we have replaced damn near everything in the cooling system. So my question is. Is it possible that his use of the epoxy plug (which is still secure in place) may be restricting the flow through the engine block and causing this overheating problem? Is it possible that a temperature sending unit is giving a false temperature reading? Or just what else could be the problem?
Thank you for any help,
Atom Ant
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Are you sure your father is not a customer of mine? Because they would do something like that.
Really my best advise is to pull the engine out. Even for a novice it shouldn't take more then 10 hours to remove and replace. In Regal you have room to access everything holding it in with ease.
One you have it out, take a flat blade screwdriver and tap the freeze plug's top edge in. When it starts to rotate, grasp it with a pair of pliers, and pull it out.
Then you need to remove the water pump. Running fresh water from the Thermostat housing (with the thermostat removed) and the water pump housing, you can tell if your getting flow. If you are, do a compression check. If it passes, replace all the freeze plugs. Get a new water pump, have the radiator flushed, and a new thermostat. As well as a new coolant temp sensor, and fan sensor.
If not pull the heads, and look for the blockage one water jacket at a time. Charles
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Have you verified that the system has been properly bled??
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