There are aftermarket switches and relays available that are inexpensive. If you need the P/N's & sources I can provide them for you. I drive my 56 daily and never take it out of OD. As Cletis stated you can't mess anything up with the stock set up.
You just have to remember to put it in reverse when you park and/or set the brake as it will roll in any other gear.
Fred


1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine