How to train for box jumps coming from a weightlifting only physique

I’ve made a bet with a friend to incentivize us to train harder. I need to increase my box jump from untrained to around 50 inches before he can lose 40 lbs. if this sounds impossible that’s okay because if he beats me it’s a win win in my book lol. I’m basically a static lifter at the moment. I surf and do a few other sports but haven’t had much cardio in years. You can check out my profile for a general idea if you care.

So far the plan is to start running for a few weeks, then incorporate hill sprints when my joints are getting back into the movement. From here I’d love suggestions. Is it as simple as adding height as soon as possible or should i focus on explosive leg lifts and movements. Are there any specific movements that have helped you gain height?

I’m 34, 165lbs athletic, former runner, with a better than average baseline jump.