964 Tweeter Mounting Depth Available?

[jaustinmd]

I've got some '89 964 door cards in excellent condition on the way! They have two sets of speaker holes and the upper holes are just under the power window switches for what I assume were 3.5" speakers. Modern tweeters are obviously much smaller and I'll have to come up with some sort of trim plate to cover the larger hole. I wondered how much mounting depth is available behind the door card - I'd rather do a flush mount than a surface mount.

I also noticed the upper speaker hole looks almost exactly the same size as the hole for the inside rotary door lock knob surround panel! Thought a neat alternative idea would be to mount a knob surround panel in the speaker hole and modify it so I could surface-mount a tweeter where the rotary lock knob normally goes! It would then match the already present lock surround and since the tweeter would be surface mounted in the recessed center of the surround, it wouldn't protrude very far and I think might look pretty good! More complicated, but if the depth is there for the surround's recess, it would be something different that would look good! (Obviously, I have waaay too much time on my hands! ha!)
John