Plate rim bolts

[Yardarm103669107@AOL.COM]

List:
Am restoring a Mason BB from 1920 with two broken plate rim screws. They are 
oval head, 5 1/2" long screws (probably #20's). M&H currently uses a lag bolt 
system which will not work with the old plate (unless I use epoxy and washers 
which I am loathe to do). Does anyone know where to fetch these screws (have 
tried every resource I know of), or have an alternative solution? Thanks in 
advance.
PR-J