In my view, if you really want to get the most out of that radio, you'd be better off spending your money and time buying or building an external loop and coupling it inductively. Save yourself some time and a bit of bother taking apart your radio....
You'd also undoubtedly be dealing with surface mount solder contacts. So you'd want to be careful.
Even a 200 mm internal loopstick won't pull in as many signals as an external 1-2 ft. loop, inductively coupled.
I have a Superadio and a PR-D5, both are excellent performers with 200mm loopsticks. Both get a boost from a 1.5 ft. box loop. Even the Select-A-Tenna will boost signals by a DB or so. The difference in reception between either of those radios and radios with smaller loopsticks (several small Realistic digital SW portables, Sony SRF-59, etc.), when using an external loop, are minimal -- in my experience, anyway.
But if you really want to put a new loopstick into your radio, the Ultralight DX Yahoo group has a bunch of guys who have put larger loopsticks into / onto their ultralight Tecsuns, so that would be the place to go.
Even so -- many of them use Ferrite Sleeve Loop antennas to DX with, inductively coupled to their radios.