There are two ways to make your single-filament park lamps act as runners & turn signals. The easy way is to install a SignalStat load balancer which lets you run two leads into a single-pole socket. The cheap way is to pull the sockets out of the housings and replace them with dual-pole sockets (for 1157 bulbs). Both solutions can be found at NAPA.
Even if the '54 has the stock turn signal assembly on the column, you probably won't be able to use it on the '50 steering column without minor modification. There's a notch and extra holes in the later columns which locks the signal assembly in place and allows you to run the wires inside the column to the underside of the dash. I believe you'll find that the clamp-on aftermarket switches have color-coded wires that match both the stock signal assembly and the later (turn signal equipped) wiring harness.
