I'm pretty new at this, is it worth buying roller rockers to replace the stock rockers? would I gain any HP? If so what would be a good brand? The engine was rebuilt about 2500 miles ago, 402 big block.

Need more information: street engine (hydraulic cam?). If so, IMHO, roller rockers are a waste of money with very little HP gain.

As for brand fo roller rockers, I am a die hard Harland Sharp fan. Best on the market for the price. Crower and Isky make good ones too. Any other brands are second best IMHO.

Yes it's a street engine, pretty much stock except the RPM performer intake I put on it and I know the cam is an after market hydraulic cam but I'm not sure what it is. I didn't have it put in, the guy that had the car first did. So roller rockers wouldn't do much good?

if you're burning pivot balls or running a lift that requires them for the longer pivot slot,, then switch. otherwise,, they'll work ok. they do reduce friction,, but on a street type setup that's pretty much stock,, you won't really notice any more power.
if you're running any kind of spring with the stock 5/16" pushrods,, you'll probably start bending those first with any kind of rpm's.
so,, like my dad use to say,, if it's running fine,, leave the hood shut. of course,, i never listened!!
they're a good strength upgrade though. one you won't worry about after you do it. i run the harland sharps also. the bbc's are rated for 800#'s of valve spring on their website. hope it helps.

If its a stock"ish" motor i would just leave it alone....

I use the Scorpion roller rockers on everything i build, work great & are dead reliable for me so far. Currently have them on the turbo motor as well.

-Carm