"years ago " If you have used it years and it is finally showing some wear why not just sand it and reinforce with glass and epoxy like the rest of us? .....

.

Brass strip would be some weight and money, and if "popped off" due to being held with only epoxy, well, it would be on the bottom of whatever lake or river you happen to be in.

Better: Very protective and quitck and easy to install this type of keel guard.  Several options and vendors available.

https://www.ebay.com/i/174098467547?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=174098467547&targetid=883069117886&device=c&mktype=pla&googleloc=9027998&poi=&campaignid=9426387489&mkgroupid=95112702865&rlsatarget=aud-412677883135:pla-883069117886&abcId=1140476&merchantid=6296724&gclid=CjwKCAjwnIr1BRAWEiwA6GpwNfzXvUT7BG4ZApxAPdcXWpx9jAr2HyTXOFG4qFkP0_HbweHUWYg94RoCcugQAvD_BwE

I agree that wood screws would be insufficient unless they went well into a very beefy fillet.  If you really want the metal solution, I would bed the metal in thickened epoxy AND secure with small machine screws through bolted.  You will need to drill-fill-drill the holes to protect the plywood from water intrusion.

I have used two different approaches for rub strips.  The easiest is a pliable plastic product called KeelEazy.  It comes in a variety of widths and colors, and is easy to apply and remove with a heat gun.  It is not a permanent solution because you will haver to replace occasionally depending upon useage.  Top picture is KeelEazy on my wife's Frej.

A more robust solution is the rub strip kit that CLC sells.  It is basically an epoxy/graphite slurry coating over dynel cloth.  This takes a little work but it can look nice if you are careful with masking.  It will stand up well for normal use as long as you are not routinely dragging the boat across pavement.  Whenever I repaint/re-varnish, I hit these strips with another layer or two of slurry to replace thickness and keep them looking good.  Bottom picture is my Wahoo with the CLC rubstrip on bow and stern.  This picture was taken at the start of the Suwannee River (26 mile) Challenge a couple of years ago.  This race includes a portage where I literally grabbed the bow handle and drug the boat for 1/4 mile through the woods.  The rub strip held up well and and looked as good as new after a slurry recoat. 

���I usually scratch up the rest of the hull and have to do a little repair about twice a year. I have habits of surfing and dodging under docks and trees and oysters, etc. If you do go to the abrasion strips be sure to prep and glue properly. I've seen several that were not done well and came off of the boats in the canoe club. If this is a real concern it seems like we ought to embed a skid strip of plastic like my Old Town Egret, kayak, did at the stern.