[roughrider]

Thanks for all the excellent replies. To do what I want, it seems i must dump the 4-wire turn signal unit and get a 7-wire.
My setup for my '31 Dlx Coupe (6 volt pos gnd):

Cowl lamps have the Turn Signal Adapter Kit with a new reflector that has a larger hole in center and socket for dual filament bulbs. Mac's p/n 28-21082-1 on sale now at a discount. Other vendors have this same kit.

Replaced the Cowl bulb with an LED from LEDlight.com,
SKU 97465W...1154 Bulb LED BAY15D Base, 6v, 2.6 watt, white 6000K. This is search light bright, hard for anyone to miss. Bulb is big but just fit thru reflector without touching the glass lens.

Tail lamps are all red LED, original look body. They are made by UPautoparts.com and sold by many vendors.
See photo. UP part #FTL2831LED6-AL
And, yes these babies are Very bright. 2-wire like the original; tail lamp and WOW brake light circuits.

The electronic flasher (for LEDs) came from LEDlight.com.
SKU 84787, Flasher LED 6 volt Pos ground 3 terminal.
It works without using any load resistors. These guys know Model As and are very helpful on the phone for vintage cars, 6 & 12 volt LED bulbs, flashers etc. Have stuff I could not find anywhere else. Don't forget to attach the small ground wire from this flasher to the body.

Next: Order a 7 wire turn signal unit. This should allow me to use the tail lamps as Both brake and turn signals
with out adding extra lamps to the bumper. Hoping.
Thanks all.