Gears?

I'm thinking about getting a set of gears for my 1994 5.0L v8 convertible. I have a custom bent exhaust, flowmaster 40 series mufflers, and a CAI. I wanna go with something bigger than 4.10's in the rear. I've been thinking about 5.13's but would they hurt my engine or tranny due to the load on it? 5.13 is huge and I know i'd be flying off the line which would rock but I don't wanna end up hurting my car. it has 123,000 miles on it and the rear posilok is still good. [get the 2 wheel peal still ]..
anyway, any suggestions/feedback would be great.