Re: 400m Rebuild Advice
I don't know how much help I'll be but I'll tell you what I know. I helped my dad overhaul a 400 from his 1978 Ford F-350. The truck only had 35,000 miles on it but he bought a fifth wheel trailer and wanted some extra torque to drag it around. He did an RV2 (generic term I know but I don't know the specs) cam, Edelbrock SP2P aluminum intake, recurved distributor, mild porting of stock heads, retuned Holley carb. He left the lower end alone other than replacing the bearings. It made quite an improvement in towing capability and it made the engine very responsive. The issues we had were that the engine was tough to keep cool and it was tough on main bearings. After around 85,000 miles on the truck (only 50,000 on the overhauled engine) the bearing started to go and it would lose oil pressure on a hard sustained pull. I put new rod & main bearings in it at that time but replaced the engine with a 460 at the 110,000 mile mark. The 460 is better suited for the heavy duty work I need.
Hope that helps a little.