upgrade for stock brake booster on 1970 C20 Camper

[swnicholson]

Hi, I have a 1970 C20 Custom Camper and am a wrenching novice. It's something I watched my grandfather do, but never did it myself. Now I've inherited his pickup and I've jumped in and am loving it. Can see how this is very addictive This is my first post, hoping to get some feedback.

I'm looking to upgrade the brake booster. On the SPID is "J70 Brake Booster Equip", although I'm not 100% sure the one that's in there now is factory. Photos attached. I think the wetness in one of those photos is from the recent bleeding I did, but I should double-check there isn't some other leak.

Where should I look to find an upgrade to the booster? I did a lot of research and nothing turned up. Will I have to replace the lines?

Thanks!
-Scott