40 deg flaps - marvellous!
Correct..it's obviously a typo. I love scanning the POHs in my "All those Cessna 150s" book. If you must have mph, I note that the 1973 C150 POH does indeed say that for short field landings use 40 deg of flap, enough power to control the glide path, and approach at 60 mph. After clearing obstacles, reduce power and maintain 60 mph by lowering the nose. In kts, the recommended figure for the final year 1976 C150M is 52 kts.
You're missing a lot if you don't use the 40 deg flap setting, at least sometimes. On marginal strips in outback Aust I've found it excellent, giving great and precise approach control. On one strip, a curved final to miss the windmill was required* , and my old C150F with 40 deg flap was just the ticket. 10 deg on takeoff, bled off gently as we picked up speed, was a good way to get out, too.
You do need to get into the habit of getting rid of flap more than 20 deg if you want to go around, but that should be second nature for all 150/152 pilots. Do yourself a favour and hop in with an instructor to explore one of the best features of the C150. You'll have a lot of fun, and won't look back.
Cheers.
*In case you're wondering why the wheat cocky didn't get rid of the windmill, it was his way of keeping pilots away from the single wire earth return power line. Perverse, but effective.