Add it up,
4-1 kit: 600.00-700.00
HD32 spline rear: 350.00-375.00
HD32 spline front: 150.00-175.00
machine work for the HD front yoke: 1250.00-160.00
Now you say you dont need the HD yoke's then expect to break them, alot.
They are small and cant handle the 5.3 power and 37's.
So add it up the smaller numbers and its close to 1200.00 and thats not even including the rebuild for the dana 300. Yes you need that to, any dana 300 is over 23 years old now and will need a good going threw. So add another 150ish to that price.
If you keep an eye out for a used atals there in the 2K down range and will have all the beef your looking for. Or check AA for deals around X-mass they had a huge blow out last year Atlas 2 Speed Transfer Case (3.0:1 Low Range) | Engine & Transmission Conversion Adapters - Advance Adapters
Now that is a 3.0 atals for 2K new, yes its not a 4-1. I would rather have a 3.0 atals than a 4-1 300.
Its a case that will be with you for life so spend the money right from the get go, IMO.