I'm just in the process of installing a 451" and was in your shoes too. I went with Neils recommendation and bought a new Dana from DrDiff. Buy the time you build up a 8 3/4 you will be into the same or more than a new Dana. The Strange Dana's are lighter than the original Dana's but do not give up anything in strength. Also you can order/upgrade to a true trac diff and pick your gears. 1350 U joints, bigger tapered wheel bearings, etc... ( that's how I odered mine)
It just made sense to me about the Dana. I suggest you shop around get some quotes and do the math.
I sold my 8 3/4 before I owned 2 of them
.... while it was still worth something!
With a new Dana you will know for sure that you put your best foot forward and won't worry about breaking it. With the 8 3/4 I would always be wondering?