Dilemma on case study

Have a case study with a fund that does GE/infra. Asked me to pitch a potential investment of my own choice, including the normal IC components, but also a return analysis, which is the biggest problem.

Wanted to reach out if anyone had experience on such and was curious on how to structure the potential investment (ie. quantum, structure, any downside protection) Unsure of how creative/realistic I should approach this.

Obviously I would have to pick a public company, but the more I think about it the harder it gets in terms of structuring the deal (take private, minority investment, buyout, etc. but honestly seems difficult considering the firm's usual ticket size)

Any color/insight would be greatly appreciated.