I don't want to be the bearer of bad news but many times heavy-duty loader buckets have a number of differences which begin with design details that you may not be able to see...thicker steel sheet, tubular sections at the heel and the top for torsional strength, thicker cutting edge, and reinforcements along the end sheets.
Many John Deere compact loader buckets had thicker (3/4") cutting edge on the HD buckets while the standard buckets only used 1/2" cutting edge. Yes, drilling the edge is pretty easy with the right equipment. I wouldn't recommend it with a regular hand-held drill, it is a job for a magnetic drill press. Your welder may have a magnetic drill press or know where to source one.
I would recommend that the welder "box" the heel and the top portion of the bucket...if the bottom isn't already. You will lose some bucket capacity after creating the boxed tubular sections, but it will make that bucket much stronger. Also, have the welder run 3/8" x 2" flat from the base cutting edge along the front edge of the end sheet and end it at the top "boxed" section. The resulting bucket will be much stronger, but not indestructible.