Pitching washed yeast

I just want to verify that I am thinking this through correctly.

Assuming that my washed yeast has about 2 billion cells per ml which is the default setting for pitching from slurry on Mr Malty.

If I go to Yeastcalc.com, assuming I have 50ml of slurry with 100 billion cells I plug 100 into the initial cell count with the production date set for the date that I harvested the yeast, april 1st, it tells me I have 71 billion viable yeast cells.
For a 5 gallon batch with a gravity of 1.05 it says I need 175 Billion cells.
So with my 50 ml of washed yeast it tells me I need a 2 liter starter with a gravity of 1.037 to give me the 175 Billion cells I need.

Is this correct?
Should I assume 2 billion cells per ml and use the harvesting date as the production date?

Anyone?
Mostly just want to know if I should assume 2 billion cells per ml and what I should put for the production date and viability %

Mr.Malty's defaults to 2.4 Billion, but it differs from strain to strain. Some yeast are simply bigger than others. Without a counting I think your defaults are just fine.

Thanks biodarwin. Glad to hear it!