Dog loves kitten too much

I have a female dog who we are having some issues introducing to our new kitten…but not in the way you'd expect. She is a nine year old female who came from a puppy farm rescue. She was spayed when she was around five and we're not sure if she ever had a litter but I'd say it's likely from her age when she was rescued and her absolute obsession with puppies. We got our younger two dogs as puppies and she adopted and raised both of them as if they were her own. When she meets a puppy out on a walk or at the vet she goes mental.

The good news is she's not wanting to chase the cat, she's not over threshold, she's not fixated, she can move away when asked and take food. She's just beyond excited in the same way she was with the puppies. She wants to lick the kitten all over and play with him but she's 14kg of solid muscle (Staffy) and will crush him if she just goes into him like a bowling ball.

We've tried having her on the lead with the kitten loose but the restraint seems to make her worse and more frustrated. We've also tried holding the kitten and letting her loose and she's better this way but the kitten eventually gets bored and wants to run around. We've also tried her with a muzzle but the issue isn't really her getting to bite the kitten but wanting to press her whole body into it and/or wrestle with him.

We're seeing some small signs of progress like she's stopped crying constantly to see the kitten if she hears him moving around and we're making sure meetings with the kitten involve treats for everyone and end on a positive note before anyone gets too fed up.

I should probably also note the kitten is absolutely unphased by anything she or any of my other dogs do. He came from a breeder who had a dog so just sits and looks at her when she does anything and isn't bothered by her licking him. My other dogs are more normal and we've just been doing standard cat/dog intros with them which are progressing as expected.

I'm just wondering if anyone has any experience with this or tips. I feel so bad for her because her heart is in the right place and I know she'd be a brilliant playmate/surrogate mother for the kitten, its just helping her find how to interact with someone who isn't as robust as a puppy!