I have a 500 Cu. in. Cadillac. The reason I haven't installed it in a truck is because I would have to fabricate a compressor bracket and drill a hole for pilot bearing. I am in the trucking business and occasionally I have to get a tow. Have you checked with towing companies. I usually pay about $5 a mile. We care capable of towing our own and whenever I buy a play toy, I tow it myself.
https://photos.app.goo.gl/8Jo5ykDpvRS8Jd8bAPossibly you know someone who is in the trucking business
V6 heads were not prone to cracking. I would suspect a head gasket or a cracked cylinder. Buy a cheap bore inspection scope. Pressurize the radiator, remove the spark plugs and see if you can find where the coolant is coming from. If the engine is junk, you really need to find a truck engine with an air compressor bracket and a hole for a pilot bearing.
