Be advised... my 258 had 130 PSIs across the board, and I had so much blowby it was coming out of the dipstick tube. We are swapping in a 4.0, and although it would not be difficult for someone with experience, it is my first time and taking MUCH longer than I expected. It's my opinion, but pretty much any 258 you get is going to be used, unless you find a new rebuilt one, and I think that would be hard to find. If you have the time I would rebuild yours, or have a shop do it. I really don't know what it would cost, but someone else can give you an idea. That's the only way you will KNOW what is in it, unless you buy an altogether new motor.
Go Fish! <*////><
But the right word at the right time... "Hey, give me a little hug!" That's the difference between lightning and a harmless lightning bug!