I think you will need to chamfer the crankshaft counterweight at the bottom of #6 cylinder around a 1/4 inch on the # 4 main bearing side to clear the bottom of the block.
I've had more than one 440 crankshaft machine to fit into 400 blocks along with offset grinding them to 2.200 BB Chevy rod journal size to get 3.91 stroke and had the mains cut down to stock 361/383/400 main journal sizes, I'm pretty sure the machine shop ground that edge down to clear the low deck blocks as part of the package to fit them into the low deck blocks
7.25 sounds right as far as the counterweight O.D., maybe not