Mine had the slip and slide powerglide as well and put the 4 speed box in as well. It was the good 4 speed that I think was made by Borg Warner?? Not the Opel one that had the shifter sticking out of the tranny.
Carried the same tools and parts except I never carried a head because I’d had ones the were checked out by a machine shop, milled, the block milled everything was square and it still wouldn’t hold a head gasket for 2 months so I figured why bother? I think it was the block because I had one block that would hold head gaskets and one that wouldn’t and they were both sleeved so I chalked it all up to ‘tolerances’ and what they said was acceptable wasn’t really correct.
It did handle great.
I’d though about the Iron Duke but you could get performance parts for the regular Vega engine. Of course adding power to something that was so unstable was probably unwise.
Mine had the water bath block, with sleeved cylinders, but without the coolant distribution tubes, so tended to eat the valve(s) on #4. Not as often as a gasket, but often enough that on longer trips I added the freshly machined head to the kit.
And, yes, it was the B-W 4 speed. Good thing I had made the conversion, too. I had to drive it about 50 miles out of the Oregon Coast Ranges over logging roads to pavement, then find an open shop, after my brakes failed: tranny & hand brake only.