Norbie, I was meaning a W55-57-58 won't bolt onto a W50 bell housing as far as I know (could be wrong).
I think this is what confused wants to know, will it or not.
Not replace the W50 & bell housing with a W55-57-58 & bell housing as I think you are implying, That should be fine (ignoring the clutch plate issues) on a toyota engine but since confused seem to already have a custom bell housing for the commowhore he needs another GB to bolt to it.