Plus rep for Stu too!. One big ol rep-fest.
Definatly! The W58 was just as an example, the first G/box I came across that is able to be bolted to a K block and that had similar 5th as to what Josh is talking about
But realistically, thats the cheapest option... 500-700 for a W58? 100-400 for a bellhousing. Plus a few other bits like clutch, mounts etc. Say $2k max, you've got an already engineered gearbox, that you know isnt ever going to break with any K engine.
As opposed to a $2k K50 that may last 2seconds after you take off down the street.
Just play around with diff gears till you get what you like, Piece of piss really.