i have a 4.3 in my 85 blazer. lots of mods. i also have another 4.3 with the same mods with one addition. roller rockers. i am wondering if i can just pull out the rockers and swap them.

also, what advantage do roller rockers give me?

 

Depends on the rocker and how it is attached to the head. If your head has pressed in studs... I would not trust them, especially if you have increased the spring rate (different valve springs) or seat pressure (shimmed your springs).

As far as the benefits of roller rockers. Well #1 is reduced valve train friction. There are more, but a quick google search should turn up more than enough reading material to suit your needs.