Replace rocker?

[K20rookie]

I've decided to tackle the body work on my 70 K20 restoration, and have zero experience with metal fabrication or body work. I'd like to learn how to do it, plus I don't really have the funds to pay someone else.

I'm thinking I will need to replace the driver's side rocker panel and both footwells, but I wanted to get confirmation from you guys to make sure I'm heading in the right direction. I plan on buying a mig welder and teaching myself how to do this.

I was hoping I could get away with POR-15, but after closer inspection it looks like that won't be an option. Any advice would be appreciated. I thought I would start by flipping the cab on it's back and cleaning/POR-15 the bottom, and then flip it back up and start on the rocker.