I bought a 4.3 GM crate motor and have had fantastic luck with it. I would NEVER buy a Jasper. I have 2 auto tech friends whose shops sell Jaspers, and both say the return rate on them is quite high, and neither bought one when they needed engines, even though they would get it at shop pricing. Rebuilding it yourself is an option, but I know the GM crate motors are hand built, not like most the other GM motors you get in vehicles. You can probably save money by doing it yourself, and its not something so difficult to do, but without opening it up and see what all needs attention its hard to say. If any journals got starved for oil, if the webbing in the block got whacked by loose rods, etc, if the crank/block needs re alignment.....maybe a block......who knows. Plus time is probably an issue for you as well, so buying a crate motor might be the ticket. Another thing to consider is there is a core charge on your old motor. Seems mine was like a few hundred dollars, but my 4.3 cost me about $1500 with me driving to Berger Chevrolet and picking it up. I also had to return the crate it came in, all of it, every piece, because if I didn't there was a core charge on it as well. Not sure this helps, but hope so.