I have the original 383 motor from my 71 road runner that I'm trying to save and looking for help. The block had 150k miles when I pulled it and i suspected it had to much thrust as it's a 4 speed car. The crankshaft counter weights contacted and gouged the mains and killed the crank. I took it to a machinist to have it cleaned and checked he said the block can be saved as the thrust cap did not get scored. The machinist said this is common with 4 speed cars. Any experience out there?