489 R&P, good choice?

I know what I need to do now & I very much appreciate the high level tech and yes it is open wheel P205/70 or 75/15 required. iirc one of the chebby boys said they were running in the fives. back to my original Q, the reason I asked about the 5:13's is I have some 5.57 in there now but I cannot get the axles in all the way. I've never ran em just what I had in my stash. I looked in the sides & I see a round area with a small hole in the middle (that the axle end would butt up against I imagine) which a guy said is normal. Any thoughts? RR