I don't believe they are close to the same. After looking they are not.
This is Brothers page for the ignition switch for the 61 if it opens up to the right page. I see that they must have updated their webpage as it is actually rather simple to navigate now.
https://www.brotherstrucks.com/Switc...products/1810/
If that doesn't work go 60/66 Electrical, switches and it will open.
This is Classic parts page for the same thing. Note on either you will need switch, Bezel and lock cylinder if your lock cylinder doesn't match the one in the photo on the page. "universal" switches suck when put in any Chevy truck as they always want to turn in the hole and have wall locker keys in them.
https://www.classicparts.com/Switches/products/206/
This Rock auto page should show the Goodmark number for the correct switch, Looks like they are out of stock there but that number entered in a search might find one.
http://www.rockauto.com/en/catalog/c...er+switch,4700