Here's the brake board for the OEM fixture. The LW fixture is about 1/3 inch shorter and bit less wider. Shouldn't be an issue shrinking the board to fit.
The connector may be an issue though because the socket encroaches into the cavity and the connector + pigtail is quite long. I may have to make my own connectors using empty connectors like this one. Not looking forward to making connectors as it requires 2 different types of wires: solid wire for the connector and stranded wire for the pigtail. I have a couple of ready-made connector+pigtail units ordered.
Also the 3157 connector is not polarized like the 1157. Thus I may need a full bridge rectifier instead of the simple steering diode used on other LED boards.