One thing to keep in mind is that the 426 bore size is 4.250 stock, the 440 are 4.320, .070 bigger than the 426 bore, that is only .035 per side How thick do you think the ring ridge is? Maybe boring that block to 440 stock size and buying a set of stock 440 bore 6 pak pistons to use with your 906 heads may be a viable option to build a nice relaible street cruiser that will still put a smile on your face when you floor it After all, there are some things a man can never have to much of, fun, money, traction and horse power