Whats better,grinding a crank or line boring?

First the counter weights need to be turned down .180-.200 to clear the block.
Second the mains are turned down to 440 specs and there crank is not any weaker at all.
Line honing the block is to ensure the main cap bore is true and straight to make sure there is no movement of the block to cause premature bearing wear.
Do not bore the 400 main cap bores,as you will have to redo the bearing tab to fit the 440 bearings.
Turning downn the 440 crank mains to a 400 allows you to use stock 400 main bearing and stock rod bearings.
Mrmopartech