Tires for the Bonnie

[Clark]

I'm pulling my 1968 Bonnie out of storage for the season and I noticed that the K70 sidewalls are all cracked and will have to be replaced.
I was wondering if anyone had a suggestion about a more modern tire pattern that might handle a little better. I'm not looking to road race, just looking for tires that will let me push the bike a little more that the old K70s

Thanks