If good sound and originality is what you want and money is somewhat of an object BUT you are willing to spend more a few more $ than a standard budget system, take the car into your local custom car audio shop and a reputable one at that. Tell them what you are after and see what they have to say.Also ask them about aftermarket decks and see what they have to offer as a solution to cutting your dash.If you are planning to keep the car for a good length of time you may want to go with a deck you would cut into your dash with. These pros "should" be able to offer you a clean,unbutchered installation as well as superior sound. It probably will be a great challenge for them on your car as they probably do mainly if not all modern cars and especially being a convertible, good clean powerful sound in a car that usually housed an AM,one speaker stereo with no where to really house any other speakers.Ditto on the cross over and tweeter/high situation.Look to door speakers,pillar speakers,well cover speakers,under the dash speakers,kick panel speakers, under neath the seat tubes,behind the rear seat subs(however i have found that to be less affective) Subs for the trunk.Explore every nook and cranny of your car for locations.Unfortunately if you want a lot of sound in a convert, its pretty much put speakers in places they originally would not be or lug a huge box in the rear seat around and a few other hidden speakers.For this project unfortunately you will need to comprimise either way you look at it to keep the originality or go for the killer sound.Check out a shop thats won awards for their custom sound and see what they can do for you and at what price.

David