Whats better,grinding a crank or line boring?

EG; 400 block fitted with a 440 crank. I see that there are two ways to do this .First is to turn the 440 crank down to 400 main size. Now this would weaken the crank some and also usually means handfitting main bearings.

Other method would be to line bore the main caps and saddles to 440 size and simply drop the crank in using stock 440 bearings. Of course this is going to remove some material from the saddles,but is it enough to worry about? Im thinking probably not as the 400 has awefully thick main saddles.

From a strength point what is better?

Which method would have the edge in cost?

We are talking a fair amount of material off the crank to fit it to a 400.