OPINION TIME
Remove lens. Measure the space available INSIDE the fixture. Height by width.
Find the combination of SMD's on plates (the plates vary by the number of smd's mounted in them). The combination. Whatever sizes it takes to CRAM the maximum number of LED's into the space. Take the stupid bulb mount out to get more space, if you need to.
Found out by trial and error that pasting the plates directly to the lens rather than to the base yields A LOT MORE LIGHTING. So you got dozens of bright points shining through the lens.....sue me. It's worth it.
The micro wiring that comes with these plates is hard to work with. You need to SOLDER the wires to a common junction. Easily done on a kitchen table because you are working with the LENS and not the base. 18 gauge makes a fine connection to the whatever color positive and negative wires that feed your fixture.
But don't overlook pasting the plates to the LENS. For me, it yielded at least TWICE the light. Those plastic lenses are garbage. The right way to go would be leaded crystal glass. But if you paste the plates to the base you might as well stay with incandescent IMHO.