Tinman, I have reused housings that look like that with no issue on my smaller motors. I would lightly clean with scotchbrite and use an oem impeller though if you do.
1954 Evinrude 7.5 HP
1954 Evinrude 15 HP
1954 Gale 12 HP
1955 Johnson 10 HP
1956 Johnson 10 HP
1956 Gale 12 HP
1956 Evinrude 5.5 HP
1958 Johnson 7.5
1960 Evinrude 18 HP
1973 Johnson 6 HP
I would probably just smooth it up with some light emery and try it out. How is the SS impeller plate? Consider replacing the housing/plate if water pump performance is weak..