'69 rods, or thicker '73 ones?

I'm going to rebuild my '69 318 and was wondering if I should keep the stock rods or see if I can score some of the heavier '73-later rods.
I'm sure the ones I have can stand the build and I'm not planning on gunnin' the engine to 6,000 RPM (all the time :-D haha ) but seriously should I get some heavier ones just as a little extra insurance in the bottom end or just work with what I have?