426 small block

340six said
4.100 with 4" stroke would be 422 or am I wrong

4.185 X 4.18 = 460.54

4.2 X 4.18 = 463.29

4.2 X 4.25 = 471.05

The trick there is a block that can use a 4.2 piston in its bores and finding or making that once available 4.25 sbm crank.