Possible 451 build options

You'll need to cut down the counter weights for block clearance putting the 440 crank into the 400. You can do it cheap with a grinder if it comes down to that. I took .100 off and that wasn't enough. The edges of the CW's needed beveling and the block needed some relief with a grinder. Turning the mains down is essential, doing the rod journals is fine if you have 2.200 rods available in budget. Honestly, unless you have cheap crank grinders about, just buy a new crank, like a Molnar or even an Eagle or Scat.

If you like, I have an old school offset welded factory crank that I collected in some horse trading. It seems it was supposed to be 4.150, but when I put it in the V blocks on the balance machine and measure, it measures 4.10x. Polish's up nice, decent crank from back in the day but still factory low carbon steel. Used with factory heads, should be fine with huge torque. I also have a set of Icon IC 827 pistons for 4.375 bore. Unfortunately the jackass I bought this engine core from used a ridge reamer like a chimp and it needs 4.402" to clean up. So I have surplus pistons and rings. Special order, no return. So add 6.760 rods(you can use the 440 rods) and you can have a 500 inch motor. PM if you're interested, I can balance the assembly if you like. Figure about $1050 out the door unless it needs heavy metal, which I'd doubt. S/F....Ken M