Hello all I am new here.
If all you have is a hole that size its easier to have it repaired.
Ironic that a 50c hole costs $50 to fix. . If you are lucky!
Classic fabrications list them. Yours is the same as La Salle for that year.
Take a pic of the affected area. I just had a look at my floor. Very simple to replicate the pattern over a hard edge with a dolly and hammer I would think. Love those 39 front ends. Believe it or not management of the era decided that the 39 front end was the least Cadillac signature front. Personally I think it is the best. Along with 53 and 57. I may be biased.
That looks like an easy fix. I would just plug the holes with a mig. Just do individual dots at the edge and cool with a wet rag. Don't build up the welds too much. One plug at a time. Might take 5 or six plugs to fill the hole. I had a similar cons front pan on my 53 and after an hour of welding and grinding carefully I'd plugged and smoothed all the holes.
This will certainly get you out of trouble and worst case you can always cut out the repaired section and do a more professional repair at a later date.
Sorry, it was C2C fabrications where I saw them. Look under 1937 to 1940 Buick 40 series, they are the same as your picture and $59.95. They are also on ebay under Chev number 151466237054.