Sadly you can’t migrate most of the parts over. You’ll need to put in the required Skylake CPU, the display, the AirPort board and the antenna cable harness.
I really think its cheaper to just get the better system if you really think the PCIe x2 blade SSD interface is holding you back.
To be honest I don’t think that’s it! Your SSD’s size and your systems configuration is more likely what you need to focus in on.
So tell us what you have for drives as well as your current CPU’s specs.