you can buy galv spray or just galv paint not sure how it would work out as a under coat

T shuld work ok. But. My coleges recon a well peeped well painted job wuld be harder waring. The galvo Paint stuff is ace for a hunk os steel left exposed to the elamants. Just not a car.

Galvafroild is one such product in the large range of cold galvanising paints.

It's a great paint, provided that the metal being painted has nice coat of surface rust ;)

If the surface is clean & bright, it is next to useless as are the likes of Hammerite.

These products are designed to be painted onto a rusted surface !!

If your chassis is still clean & bright, a healthy coat of etch primer will do niceley :)

The same from me Ronnie!