I have acquired a steel chassis to do a swap on my 1959 series 2 swb, if I remove front end panels, would it be possible 2 lift the rest of the body on a let's say gantry system rated to 500kg.

No, there's no strength anywhere in the middle. About the only bit you can take off as a 'unit' is the bulkhead. More work than you hoped, but on the plus side you can do all of it (except the engine) without needing a hoist.

Reassembly is rear tub first, seatbox, bulkhead - using the doors to get it in the right place/angle - then all the front.

And don't tighten anything up or drill/ream any holes that don't line up, till every panel is back on.

Speaks someone who may have made that mistake