When you say you have a music collection that you are going to copy. What file system? Is it going to have it’s own partition? What File system? Do you need to access the music from Windows. Is Windows involved?
IMO swap, root, and home (the defaults) are normally just fine for most users. But you need to answer the above since you seem to have special needs (maybe).
I have a TB drive added just for Data, but my system drive is a simple 40G drive. That way I don’t have to disturb my Data drive every time I make major changes to my system drive. I’ve configured most programs to dump downloads and music files to the Data drive.
The system drive can be 20G for root partition, with 2G for swap, and the balance can be /home on a separate partition. Although with a 150G system drive you can afford more space for root.
Are you thinking of getting rid of the 1TB drive? If not, why transfer files to the 2TB drive?
Also, if you are going to keep both drives, why not use LVM? You then have much more freedom to manage partitions to meet different, and new, needs - though AFAIK you would need to move the files off the 1TB drive anyway to do this.
IF you can live with 2TB instead of 3TB, you could use a single drive and save some power. If not, add the 1TB drive as a spare partition.
Just remove the 1TB drive, install as normal on the 2TB drive (accept the default, you will get a large /home), then add it back and copy files to the 2TB drive.