For the front, you need whatever the WMS to WMS difference is between your D44 and a DRW D60. For the rear, it depends if you want to keep the track width skinnier than the front as they are stock, or if you want to try and match the WMS to WMS as the front.
Get out your tape measure and check it out...
I don't remember exactly as it has been a while since I was around Chevy ****, but...
Your D44 should be around 69.5"
I THINK a DRW D60 is around 76.5"????
If that is correct, you would need about 3.5" per side on the front, and go w/ 4" per side on the rear as your rear is already skinnier.
FYI... 8 lug wheel spacers in the 3.5-4" variety are not cheap... probably not saving THAT much money over finding a set of DRW axles (D60 & D70) and selling your current axles... you will probably come out about the same in the end.