First of all, confirm with the company whether or not you can expect only Capital Project cases or if you need to be prepared for any case type.
Then, based on that either prepare for all case types or for just Capital Project case types.
Regardless, do make sure to be well versed in as much Capital Project content as possible! Read cases and get cases from people around the topic. Additionally, I highly recommend you explore BCG Insights, McKinsey Insights, and the Big4 site and read through the articles they've published.