Battery box - freshen up or replace

[Tidybuoy]

When I pulled my engine (5 years ago) the battery box was in pretty good shape. The car has been stored in a dry garage since then and only outside for a couple of months max.

I'm getting my engine finished up and I'm going to POR-15 the entire engine compartment and rear trailing arms.

I noticed, yesterday, that the battery box has a fair amount of rust that was not there when I initially parked the car. The part under the battery box (triangular support) is still ok and painted as well as below that (the rust in the photos under the box is just surface rust and the metal is very solid)

The flat battery box and the inside area of the fendors surrounding the battery box is pretty rusty and needs replacing. The flat surface of the battery box is brittle.

Unfortunately, I have no welding skills or equipment.

Any advice on how to repair - If I buy the parts, what can I do prior to taking the car to a welding shop? What kind of direction should I give a welder?

Any advice I can get would be great. Thanks in advance........Vern

[Tidybuoy]

Here are the pictures of the area: