the jis crank sits about 3-4 mil closer to frame on ISO tapered BB
the ISo crank sits about 3-4 mil further from the frame on JIS tapered BB

the problem with phil may be that when you move the chainline 3-4 mil further out on the drive side the left crank will be 3-4 mil closer to the frame possibly rubbing on the chainstay or the BB shell itself.....or maybe not....

and the cranks not gonna explode overnight.........they should be fine
but its alwasys best to use matching on matching