another stale gas question

["Bennett Moe" <bmoe@domain.elided>]

Ok, my R-110 has been sitting for, um, let's say 7 years or so without
being started. When it was parked, I didn't drain the gas or stabilize
it (oops). Now I am fixin' to get this puppy back on the road and the
tank and fuel pump have a chalky white substance coating them (on the
inside, that is). To my knowledge no water has gotten into the tank and
the gas is still fluid, at least what I can see of it through the filler
neck (there is only a couple of gallons tops). Anyway, I plan on topping
off the tank with fresh gas, letting it sit for a week or so, slosh it
around, then drain it and flush the lines. Should I do anything else, or
do you think that would get rid of it? The chalk seems to dissolve to a
milky white when I rub it with gas (all I can easily get to is the
filler neck). Thanks in advance.
-Bennett