Welcome to Allpar. Both Jasper and Mopar offer 3 year/100K mile warranties (however it may depend on who installs it for labor coverage).
Does it need a reman long block or short block? Is the engine you have rebuildable? Non-turbo?
The price should include the core return freight shipping.
Core Charge: $300.00
Part Number: FWD 93-1375
The 84-88 rebuilt shortblock is built for hp and reliability. We clean/check block add brass freeze plugs, forged Venolia pistons, cast 2.5 crank, sealed power rings, clevite 77 rod and main bearings, and int. shaft bushings. Rods are shotpeened, tops drilled and ARP rod bolts are installed. Add arp main studs for an add. charge. Core must 1989-92 2.5 common block, crank and rods. For motors over 400hp, we recommend using custom BC h-beam rods
It would be good to have more details than just 'not rebuildable'. That tells me nothing.
What diagnosis was done and what was determined to be the nature of the engine failure?
Overheat? Loss of oil pressure/seizure? Noise? Smoke?
Was the cylinder head damaged? A short block would come without a head, but should come with the necessary gaskets.
Marshall also offers a 3 year, 100k mile warranty. I got one from them for my LeBaron, was on sale on Rock Auto. I haven't quite gotten it in yet, but hope to have it running again by the 9th. Looks great, though they used a normal (non-turbo) block and head, and filled it with turbo parts (pistons, rods, valves are all verified to be proper turbo parts.)