You could mod the Storm to accept a folding stock. It would depend either on your technical/mechanical prowess of your willingness to farm out the project and pay accordingly. All things considered at the end of the day you would have spent either an inordinate amount of money or time to get a gun which probably wouldn't look or function all that good.
Like others have said, it was designed as a ban era gun and to meet 922r restrictions. In that capacity it did great and in its imported version IMHO works out perfectly. The thumb hole stock was tastefully sculpted and the lines are aesthetically pleasing.
If you're truly desperate for a PCC with a folding stock, sell the Beretta and look elsewhere. The CZ Scorpion, SIG MPX, JRC and the guns from Thureon Defense would probably work out better.
.02 pesos