I have a 96 f-150 with 150k. I bought it 5 years ago and it had 135k. It leaked oil but after I flushed the cooling system it started to over heat because I broke a bunch of crud loose. That forces me to pull the water pump and I ended up breaking bolts off which lead to timing cover coming off in multiple pieces. I did the timing chain water pump and whole cooling system and have been back on the road for about 10k but it leaks from my water pump job and oil leaks more after not removing oil pan and just trying to figure out which direction to go. I can pay a mechanic 1,100 to do oil pan, water pump, and transmission pan/filter. But a Jasper engine is 3,144 plus tax I’m sure and plus labor to install, or the same mechanic said he would rebuild my engine and install it for 3k. I wish I had time to do it myself but honestly with two young kids and the fact that the water pump leaked after I did that job I don’t want to ya k the engine and regasket it a d then have a problem any input would be greatly appreciated, I don’t want to spend 4K plus but I plan on keeping the truck and I would out of necessity I’m just not at that point quote yet. The water pump leaks from behind the pump i believe on the metal plate that it comes with

 

The truck would benefit if the engine was pulled, cleaned, all gaskets replaced and then re-installed. It may not need the expense of a rebuild at this time. Compression & leak-down tests would provide some knowledge to base the diagnosis on. There are many 5.0's on the road with many more miles than yours that are still running fine.

 

Your best bet is to take Slowbrick's advice and diagose whether or not it needs a rebuild (or have someone else do the diag if that isn't your skill set). If it does, I would rather have my own engine (sort of a known entity, yours 150k mi) rebuilt by a competent mechanic than to get an unknown block, rebuilt from Jasper. You're going to spend $800 to $1k just to take it out and put it back. If that is your only option, then you'll have to pay it. I would remove/install myself and drop it off with someone I trust to fix it. A 5.8 with 150k, unless it's been abused, shouldn't need that much work.