Core support sheen & battery acid

[71CHEVYSHORTBED402]

Core sheen:

I had the impression the factory sheen for the under carriage and engine compartment was satin. These are the original "gussets" for the core support and fender. I cleaned them up with a nylon brush, which dulled them up a bit.

I'm no paint expert, but to me they look semi-gloss bordering on gloss. What's your opinion on the original sheen for a core support?

Battery acid:

Thought I had a rust free body until I came to this RH gusset, which I'm 99% sure is due to battery acid. It wasted the battery tray. I still need to clean the core support, which looks solid (and white). No more than surface rust on the RH fenders, once I busted through the acid anyway.

I'm fully responsible for said battery acid. While I kept my engine compartment clean, I used to buy cheap batteries, AND always left the negative side loose for "convenience". It was a top post battery, which may have been a contributor. Just an assumption here, but seems top posts create more external acid than side posts. For any Toyota owners anyway, you probably can relate.