Here's the biggest thing to remember when talking about any karate/kung fu connection.
The okinawans had their own indigenous art called "te" that had striking. The also had their own brand of grappling called "tegumi".
Shorin-Ryu was based on what they liked about kung fu and incorporated it into what they were doing. This is why you will NEVER find a kung fu style that looks almost like any of the karate styles, or a direct kata from a kung fu style in karate. They didn't import and teach "kung fu". They learned aspects of it and added it to their own thing. In Shorin-Ryu, they named certain katas after things that they learned from chinese martial artists. Wansu, Kusanku, Chinto for example were inspired by what they learned from Chinese martial artists.
If you look at a kata like "Seisan", it was an old okinawan kata that was used as a template for what they like, so you will see different flavors of Seisan based on if it is a Naha based style (Uechi or Goju) or the Shuri based styles (Shorin).
"God gave you a brain, and it annoys Him greatly when you choose not to use it."