Is that a white magnum? If so then young sir there is hope fort you yet! Love those things, in fact all magnums are nice.
If you have the discs the wrong way around the gasses and the dust is sent to the centre of the discs where it has a hard time escaping which will cause the pad to float worse than solid discs.
The way they should go basically vent the hot gasses and the dust outwards towards the wheel where theres a ready supply of coolish air.
You should have used new pads. Doesnt matter if the pads were 500 miles old they will not bed in to the new disc right. However if you are gonna keep them take them out and run them over with some sandpaper.
He has stuck the axle stand under the subframe, not the correct place, but it shouldnt cause much damage unless you leave the car sitting on it for ages.
The correct place is the chassis runners, dont stick a stand on the edge of the sill, the floor or anything else. A solid box section.
Your dads 309 sounds liek a right dath trap. Had a similar thing with a mk4 escort, ford jack int he jackign point startyed jacking up and the car didnt lift but th ejack went through the sill.
