Wondering if anyone have any ideas as to where to run wires from the stereo unit to the rear parcel rack speakers..?

I'm installing a new stereo and new speakers , not putting in amps , just a standard stereo and four speakers using the K.I.S.S principle.

I have a stock standard TS 1995 Magna, and have to cut out holes to fit two rear speakers in the parcel rack and there are no wires there as standard .

Also can I replace the two small 4" dash speakers with a different set of 4" rather than cut into the door trims?

Dash speaker are a bloody pain, better off putting speaker in the door. To install dash speaker research many topics on that subject on AMC. For running cable there is a just lift up scuff plates you will see where other cables have been run :)