backer-plate for 8.75 and 10" drums

doing an axle swap 7.25 to 8.75.
Problem is my 10" drum brake set-up wont fit new axle. The bolt-pattern on my new axle has 5 lugs and old backer-plate has 4 lugs AND the bearing on axle is too large to fit though backer plate hole in center or I'd just drill holes to fit pattern.

Question is where can I find a set of backer plates for a 8.75 axle that my old 10" set-up will fit on?



I've checked my local auto-parts stores, junk yards and ebay, carigslist?