Given that parts aren't really removable I don't see how this is possible. besides if you had a SP2 to take parts from... wouldn't you just use that rather than trying to upgrade a SP1. Given different shape of the SP3 there's likely nothing that would fit into either an SP2 or 1.
See iFixit. with great skill and care you might transplant the entire guts of an SP2 into an SP1 case but what would be the point of that?
Upgrades frequently aren't even cost effective in systems that are upgradeable.
Check online for a used or refurbished unit SP2 or Sp3 (in six months).
