Need help with Kay pickup replacement

[Mikhail1]

This was my first bass, bought by my mother in 1976, so she means something to me. The bass was old then and was in a white and brown case that eventually fell apart. The orignal pickup became unusable and I took off the pickguard with intent to replace the pickup, that was 15 years ago, so you see how much progress I've made... This bass has a very sweet neck and plays so well that I figure its time to bring it back to life, so I need some suggestions for a pickup replacement. Any help would be appreciated!

 

[Mikhail1]

The pickup is going to have to be tall fill under the strings or I'm going to have be creative about the way to mount it to the body. And I've included a shot of those tiny tuners that seem to do their job very well.