Gearing or rear end swap?

[extremesounds13]

I have a 67 3/4 ton burb that had a blown up 327 and a bad turbo 400 in it when I got it a couple years ago, long story short I swapped in a 454 and had the T400 rebuilt, I've been driving the burb for about a year and a half but I don't drive it as much as I like because at 55 mph it is pretty wound up, I can push it to 65 mph but I don't want to hold it there by any means. I'm getting it painted right now and want to drive it more when it's done. I feel like the rear end is at least 4.11 maybe 4.56, I want to either get different gears or swap the rear end out. Which is easier, and less costly? It's an eight lug so what years do I need to look for, for gears or complete rear end?