Just purchased an 1951 8n.
Just starting to go through it.
Fuel tank has about 2 quarts of fuel that has the varnish smell.
Seems to be clear of rust from what i can see but it does have a somewhat gritty/powdery residue covering the inside.
What would be the suggestions on how to handle/clean this?
I have mineral spirits in the cylinders and will be draining and replacing oil and filter as well as oil bath.
Thank you.

Years ago, I took mine to a local radiator repair shop and they steamed it out. I have not had issues with it.