I compared the extra pictures to the 904-906 Parts list I have. It is a 904, everything matches except the door. The 904 and the 906 both have ad glass panels and the window is shorter.
One thing I noticed, your pump originally had a sight glass that came out in the middle of the "V." It appears that the sight glass it self was removed and a plate put over the opening. This was done on many pumps when they decided they didn't need the sight glass anymore.http://petrolianacollectibles.com/gb%20906.htm
Could this possibly be a Canadian pump???
Could this have been a special order made by Standard who didn't want ad panels????
Not in the 1000 series.