1971 Demon with some coolant issues

Sorry to hear that. My local pick a part junkyard has yielded several engines for me. The slant 6 currently in my dart cost me all of $75.00. I put a new chain& gears in it, checked the bearings(they were good), adjusted the valves and threw it in. It runs great! If you check all the plugs for any signs of oil, turn it over, check to see that it still has green coolant in the block you can get lucky on mopar engines. This is all if you want to go the cheap route. A crate 360/380 hp would run in your car if you want to spend for it.