No, you got it spot on. From the neck down, it should take about $50 and a few hours of work. At least, that's how we designed it to be, so that there really was no excuse from any FX trooper from going EI.
The helmet though has to be replaced in toto.
Also, for many older kits it was normal to rivet the shoulder bridges to the chest/back. If you've done this, you need to drill out the rivets and replace the shoulder bridges.