The good part about flame spaying galvanising is that it leaves a kind of a rough surface.This will give a perfect surface for paint to stick on. And it is more flexible on moving parts such as a frame ,then traditional galvanised parts.
Ofcourse you will never reach the inside of the frame ,but...
I went with flame spraying galvanising on all frame parts and the axle housings when I teared down my Hj60 17 years ago. Then some good industrial ground paint and finish. Today not a spec of rust on the frame or axles. Even did the lower side of the body, like rockers and rear quarters.Apart...