5.8.4 is stable so go for that. Actually, IMHO the best reason to use 5.8.4 in favor of 5.6.1 (bugfixes aside) is the much improved unicode support.

Anyway, which version you need is dependent on how you intend to use perl in this installation. Why do you want 5.8.3 (or 5.8.4) ?

Joost.