Two Jimny Family

Hi all! 

After years of searching, I finally bit the bullet yesterday and bought a mk3 to join our mk4.

It’s a 2010 with 13k miles on the clock, totally original - bodywork and interior as close to new as I’ve seen. There is no rust on the boot floor and behind the headlights is fully intact. 

The previous owner had it stored for 6 years, only being driven to its MOT each year. 

He undersealed it with Waxoyl when he first got it and topped it up with Lanoguard more recently.

Given that it’s such an original example, I wanted to see what was underneath the Waxoyl, so started stripping some of it off the sills. 
As I expected, the factory coating is lifting, exposing surface rust. 
Everything is solid but I want to clean and treat it now to keep it that way. 
What’s the quickest and easiest way of removing the factory undercoat?

Warm pressure wash or maybe it looked clean enough.
sandblasting or wire brush or scrape off any loose rust.
Treat rusty areas with whatever product you trust. Oxal acid or something rust-milky or paint on rust type of product containing acids. Clean after if product says so. let dry until no moisture remain.

(Best is to make all rust come off and then 2k epoxy and paint but the amount of work making it bare metal...)

Treat with thinner oily product that can pull into cracks but still dries enough to take a top coat of waxyol or something thick black and oily.

Many thin coats is allways better than a thick one.
Make it very very dry from moisture before applying coats.
the more muscle removing rust and old crackly stuff the better and longer lasting result.