No because a part is made up of an fpz file (xml) and 4 svg files (breadboard, icon, schematic and pcb) thus all those files are part of the part. As well as Old_Grey’s videos there is this that steps you through making a new part (simiilar to what you are trying to do).
For what you want to do you don’t need to edit the svg likely, you should be able to do it all from new parts editor by selecting an 8 pin generic IC and changing the pin names in Parts Editor (and preferably updating the metadata tab to match your new part) to match the PIC. If you need an SMD footprint there may already be a soic8 footprint available and if not replacing the pcb svg with an appropiate svg will do the trick. Google also finds a 12F675
(search fritzing part 12F675) in projects but it is an old format and the part did not survive upgrading. Easier to start with a generic IC and go from there.
Peter