I am also looking to do the same. I have a 70 c25. We have been thinking about this for a long time and will be doing so soon. I wanted to replace all ball joints and tie rods anyway. Im going with the kit from Classic Chevy Trucks.
Classic Chevy Trucks
Kit
We priced out everything at 350$ for the spindles and everything else at local part stores and it going to be about the same price.
Im also going to cut my springs 1/2 coil to 1 coil, then if its in the budget get lowering springs.
For the back im going with a flip kit. I know you dont want to c-notch the frame but just thought you want to know how im going to do it.
I hope this helps. Best of luck. You can also search my threads for info I have recieved from this site.