With a new engine set to handle, you will have to learn about the aircraft limitations, a good insight into its performance, spin awareness, single-engine operation, new maneuverer and what not. There is so much new for you to learn and explore which you also need to master practically. For this, you will have to find an able instructors.
Now this experienced instructors will be guiding you about everything you need to know about the multi-engine system. You have to keep up with the pace and master it all.