Jerry,
You can use the ignition switch from a car or 60 up truck and use your lock cylinder. Just mark the wiring and plug the connectors onto the respective terminals on the replacement switch.
I have done a number of these conversions and have developed a spreadsheet that lists all the parts required and estimated prices and sources. If it would be of some use to you, send me an email and I'll send it to you.
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