Bill, I made one reply and then read your post again and deleted what I had typed!!
Since you plan to paint it I think a GOOD filler, something with exterior properties, would be fine until you do what you plan later.
IF you were not going to paint it my response would be different.


1937 Chevy Pickup
In the Gallery
1952 Chevy Panel
In the Gallery
More photos
1950 Chevy Coupe
Pictures!

I'd rather walk and carry a Chevy hub cap than ride in a Ferd.
I can explain it to you, but I can't understand it for you smile