Toyota Repair: 95 4runner 2nd gen, power steering pump, head gasket

Question
Mr. Ritter, first of all I appreciate you making yourself available to this website whether you are compensated or not, its still helpful. I have a few questions for you regarding my  4runner.
1) I have 140,000 on my truck and the dreaded model that has the head gasket issue, how do I know when its time before warping the head?
2) I recently started with a small power steering leak which  has now grown to empty my pump reservoir, I tried Jacobs stop leak today, how do I know if its the tie rods, pump that needs to be resealed, or a belt?
3) If its going to be an expensive 1500$ and up head job, what motor could I swap into it with the least amount of issue and best performance results
I had a similar key not working in the ignition cylinder problem as one of you other question askers in my truck, jus t a tip from a poor man, I used a small torque wrench and while gently applying pressure to turn the key as usual, I tapped the head of the key lightly and it worked, I fought with that key for two hours prior to that attempt and the problem never came back. Thank you for listening to my questions and taking the time to answer them.

Answer
The cylinder heads can warp anytime after repeated overheating, the heads need to be removed to inspect for any warping or corrosion, changing to a different motor is not only not practical but would cost more than the 4 Runner is worth because all of the electronics and electric components from the other motor would also have to be installed not to mention transmission compatibility issues, most toyota motors produced later are of a different design and toyota is not known for backwards compatibility, unless the engine is of the same family, ie: any year 5VZN engine is compatible with another 5VZN but a 5 VZN will not work instead of a 3VZN(this is the one in your 4 Runner)besides ther are emission control issues which can be a nightmare to get the thing registered.
A common problem is the power steering pump seals leaking, it can be removed and resealed with a kit from the toyota dealer.