Not dogging a D300 at all, just suggesting that one does swaps with the best parts, ones that hold value and can be used for builds and rebuilds for decades. Civilizations will rise and fall and you can keep passing an atlas on to great great grandchildren...
For the first time in all of my own personal jeep builds I finaly installed an atlas in my own rig (Horse traded for a used one)...The ability to a "dig" saved me a nasty roll over on Sledge Hammer a couple weeks ago while out there for KOH. On the waterfall at the "plaque" on sledge..I was trying the right side and found myself hanging on by 1/2 a tread from a nasty roll into the hole (ala casey Currey)when I said to myself..hey you're running an atlas...use it..I grabbed the front drive out and pinned the gas and it spun me right around avoiding the roll.......

A 300 is a strong case. to build it though...$175 for a 32 spline front output kit may be correct...but do you have the Bridgeport mill and the know how to machine the race seat? Or the know how to build a 300 at all? Not many do.
If not, ...then...you are paying someone to build it.
My shop charges $150 to just machine the race seat. (set up is most of that time)..
Is your time worth nothing?

The post was not asking how to do it cheap, just suggesting.

SD