The 15 has a soldered CPU and GPU so you cannot swap any parts to the 17. Your 17 R1 does have a socket CPU and MXM GPU though so they can be replaced/upgraded.
The CPU can only be upgraded to another mobile processor of the same generation so the best ones would be the 4930MX or 4940MX. These are fully unlocked processors if you were looking at doing custom overclocking, more than the preset BIOS settings will allow with a locked CPU. If you have no interest in overclocking then the 4910MQ is the way to go as it's basically the same as the MX processors without overclocking ability.
The GPU can be upgraded a little more though. A popular upgrade (but expensive) is the GTX 1070. The 980M comes in a little cheaper and still has good performance at 1080p. The 1060 obvioulsy sits in the middle. There are also Quadro cards that are good options. Check out the forum at NotebookReview as there are plenty of upgrade threads there. A modded display driver is required with any card higher that a GTX 880M.