I have a Chev V6 with a Saginaw steering swap.
It looks very original from the outside, but when you open the hood you can see the change.
If you are going to upgrade to the V6 I would also upgrade to 11 inch brakes, and a dual reservoir master cylinder, I would also consider front disks, but this would change the look.
I also have all stock tranny transfer case, and diffs. all rebuilt and they work fine for my requirements.