I'm suspicious of that alibaba link, especially since they list a dozen different engines. Would be a good deal if it was.
I rebuilt the 3tne84 in my 4300 for around $1500, but the block wasn't cracked. Splitting the tractor to pull the engine wasn't fun, but doable in a home shop with an engine hoist and a floor jack and jack stands. Pulling the cab was a major part. The JD manuals are critical to have, but not always accurate as far as procedures go. I.E. the manual for my 4300 didn't say the fuel tank had to be pulled (1+ hour job on a 4x00 plus pulling the cab) to get the head off because they forgot about the bolts in the back of the head that go to the tank bracket.