Need prop information for my 23 albie special please

I have a new to the family albie special with some beat up props. I was wondering what size anybody else was running as I'm going to replace these anyway. I have b3 props a 570a 5.7 with a 290 duo prop . I'm cruising at 22 mph at 2800 rpm and getting 2.75 mpg in the bay. Any help would be appreciated

I'm still on the old 280 but there's at least one of the 23 footers around who are running the duo prop.
How much horsepower is that motor?

The engine puts out 260 hp