Something I always recommend when keeping the original front suspension crossmember and changing the control arms, is upgrading to the '73 and up lower control arm shaft U-bolts. One reason is I have had 2 of the original LCA U-bolts break on me. I have been very lucky in that it was only 1 at a time. If both on the same control arm were to break at the same time, the lower control arm will hit the pavement, and all sorts of chaos will occur if it happens while driving.
GM upped the size of the LCA shaft U-bolts once in around 1971, and then again in 1973. I always go with the larger '73 and up pieces. If there was not a need for the increase in diameter, I doubt they would have done so. In case some of you don't quite understand what I'm talking about, and also for those of you that do, here is a visual comparison of an early U-bolt next to a '73+ U-bolt
This pic was oriignally posted by RockTonka in his Suburban build thread