So my engine needs replaced pretty badly and I’ve found a couple options. One guy has a 99 engine with 90k miles for $400, which I know will require a little more work to make work on my 01. Another guy has an 01 that he claims is rebuilt but he don’t have any proof of. He is asking around $1k for that engine. Is it worth the risk buying a rebuilt engine without proof? Or should I risk the $400 engine?

 

I would not buy the '01 motor.
Can you here the '99 run?
Why is it available?
If you can hear it run can you do a compression test on it?
If this were me I would use the lower end from the '99.
Assuming it is a solid engine still give it a refresh of sorts.
Swap over what is needed from your '01 to the lower end
Find a TUPY head in the boneyard. Get it checked and reworked if necessary.
Or buy a Clearwater head.
Realizing that you will probably end up spending at least $1K if not more.
But thinking you would come out on the other side with a better engine.