For 69, only the Boss models got a chin spoiler. 429 was also shallower than 302.
Dealer or customer add on for other models.
The spoiler seals tight along the valence, so I wouldn't want bumper guards pinched in there, but that's just me.
The rear spoiler was a Boss 302 option, I'd have to look thru my Boss 429 book to comment re the rear spoiler.
The 69 rear spoiler was warp prone lightweight plastic and mounted thru the trunk lid using bolts.
Again, dealer or customer add on for other models.
For 69, I recommend the quality 70 fiberglass rear spoiler with studs that pass thru the trunk lid and mounting brackets, and secure with nuts.
69 lids can be cut quite easily to accomodate the 70 mounting brackets.
I can post a pic if you like of a 69 lid I have that's been cut to look like a 70 and stands up to side by side comparison.
Sometimes the 70 prop rod is required to keep the trunk lid up with this heavier spoiler.
Depends how good you springs are.
I can post a pic of where all the pieces mount for that too if need be.