To do the conversion all you need is a new rear trunnion and receiver.
Realistically, sell what you have and buy an underfolder.
As far as underfolders go, they look a lot cooler than they shoot. Underfolders are generally regarded as having poor cheek weld and have a tendency to go wobbly. I'd take a fixed stock over an underfolder anytime.
The only folder I'd own (and do) is the AK-100 style left side folder. That one has good cheek weld, locks open solidly, and generally has no drawbacks besides requiring a different receiver and rear trunnion.
BSW