Thanks for the assistance, and big shout out to lil-weg for the crutchfield guide, makes pulling apart the car a bit less stressful. I can confirm the tweeters crossover is attached to the tweeter. Had to break out the dremel to make a hole in the tweeter cover and massage the dash under the cover to get everything to fit.
The speakers I used while not top of the range by any means (Alpine s-s65c) used an inline crossover so I managed to wire that in at the tweeter with plenty of room behind the dash under the cover to stash the wires. Thankfully tweeter and door speakers are wired in with a plug, so was able to easily reuse the plugs and make the speakers easily removed.
I was also able to reuse the foctory door speaker spacers by cutting out the old speakers (makes sense if you try it) and then gluing the alpine adapter plate on to that - creates a really good seal without having to drill new holes.