Powder in gas tank neck?

[gotmud]

I've been working on finishing up a 64 C10 for a while and am getting to the gas tank. The tank, from the PO, looks like it could have been new but I dont really know. Pics attached.
My question is about guessing about the inside condition. When I look down the cap, I see white residue that is powdery.
Do you think a clear fuel filter will catch this once I start filling it up,
do I need to pull it and clean it some how,
or do you think I need to rip and replace?

I got it cranked today and she sounds so sweet....but I am just using a fuel line, re-routed from the fuel pump, stuck down the neck of a plastic gas can.
Thanks
Glenn