4 bolt mains

I used em on mine. Have not had any problems, but looking at it there is not much meat on the block where the extra hole is tapped. Would not do it again.
They say it pulls from the sidewalls of the block and not the flimsey main web area , but do the outer bolts really reach that far out. I have seen some kind of girdle that bolts on the main caps, could that be something to use?