Fuel Tank Dent Removal

I'm trying to restore a Petter PAZ 1 which has a rather badly dented top around the filler neck.

I have no experience in dealing with damage of this kind. Do folks here think it's repairable?

Any tips or suggestions gratefully received.

Make yourself a spoon from a thick piece of metal, bend the end that goes in through the hole and polish the spoon end so as not to leave marks on the metal, you may need to make a couple of different sized spoons, you might like to polish the flat face of a small hammer to use with the spoon from the outside.
Push the internal dents out with the spoon and use the spoon as a dolly with the hammer to flatten raised surfaces.

Maryalice