Thanks for all the comments. With a 3 speed bike, I would either need a springer fork with a drilled hole for caliper brakes, or an upgrade to a front drum brake. Or possibly a coaster brake three speed rear hub. None of those sound like options I want to pursue. I suspected Schwinn never made a spring fork drilled for front caliper brakes.
Not saying I am going to do this project. Target bike would be my '63 Tiger 3 speed. I was just wondering how difficult it would be to do, and what the source of a good spring fork would be, etc. It does appear there was a clear break in the spring fork production, maybe a couple? I see from catalogs and price lists you could get an all chrome spring fork as an "accessory" from at least the mid 50s into the 1964, the last year of the spring fork Jaguar. I assume 26 inch wheel spring fork production ended with the Jaguar. Then the Krate spring forks were made for those, but again dropped when those were ended. Last would be the 1980/81 spring forks for the Deluxe Cruiser for those years before the Chicago factory was closed thus ending Schwinn spring fork production. Does that roughly sound right? Interesting about the noted differences between 1950s/60s spring fork production and 1980/81. I guess I'd have to compare those close up. Pictures of the 80/81 cruisers don't look different from middle weight spring forks of the 50s/60s, at least in terms of construction. Maybe the chrome plating wasn't as good in 80/81? Will read the thread Jeff posted on spring forks. Great to learn new stuff!