Dent Removal

there are as you probably know puller kits that work on suction but these are meant for larger areas such as a car door. the other option could be a slide hammer, its a bit drastic as you need to drill the tank to attach it (and in my experience noone wants to weld an old petrol tank) judging by the dent it would probably take two or three goes. the other slim chance is to make a tool with acurve on the end (like a wrecking bar) and try to gently lever it out from the inside as you do this you really need a dolly in your other hand to control the process from the outside (its a skilled job, marvelous to watch someone do it, easy to make an arse of when you try). when all is said and done chances are you’ll lose the paint anyway and for this reason filler, sadly, might be the option.

A good dent men could vastly improve that dent, but in my opinion you need to get a really good painter with dent removal skills who could dramatically reduce that dent and apply a light skin of filler then repair your rusted area and repair your scratches and chewed decal, your decal can be saved by only doing a localised paint repair, then when the rusted and repaired area of the tank has been localised painted, your tank can be lacquered all over.