[burnin oil]

Internal balance crank makes the 400 like any other small block. Then you run a standard 350 balancer and flywheel. When I did my last 400 I spent a big chunk of change, about $1700, and got a SCAT rotating assembly. Sounds expensive untill you realize that you end up with a forged crank, better rods, forged pistons, rings, and bearings for the price. I do not know if they make a internal balanced cast crank but the 9000 series are very good and cheap. Rod size is determined by the piston used. You can plug you info in Summit racing and look at 400 pistons by rod length. Some people on here will argue this but I would try and keep the compression at 9.5-10:1 but some feel less is better for a mild build. Personally I went with the 22cc dish pistons and think I missed the boat there. With 64cc heads I need to run a thin head gasket to keep my compression up. I should have gone with a 13cc piston and a standard head gasket. A 5.7" rod should fit without problem but a quick mock up will verify this. I never tried a 6" rod but from what I have seen you will have to relieve the block in a few places. Back to pistons. Make sure that you dont get low tension oil rings or the narrow racing ring packages. You want a long service life that doesn't burn oil or leak compression.