- That link is for assault rifles, not pistols
- The section of the law discussing pistols stipulates a minimum barrel length of 6" and a minimum overall length of 10-1/2" even for single shot pistols
- The law cited requires that the conversion be performed by an 07 FFL or that the firearm be modified before it enters California.
Does your plan satisfy all that?
And where in that law does it say anything about being legal to UNconvert it once you have it?