Rear tail lights centre panel

I've tried doing a bit of that.
I found that fitting the original 'honeycomb' center to the later lights can be done, but even if you are careful it still tends to look a bit rough with unavoidable gaps at the ends. (See pics)
When I did mine, after careful consideration I soon removed it, but not because of the gaps.
It just didn't look right; the reason being that the early garnish is 'square oriented' and matches the early square lights, and the later lights are more or less 'round'
Remember the old saying about a 'square peg in a round hole'
Anyway that's just my opinion.
 
At one stage I also bought an aftermarket Kouki center garnish without reversing light holes or keyhole that was made of fiberglass. It was a bit rough and needed modification to fit properly, but without the reversing lights or MR2 letters I thought it just looked a bit plain, so I spent a lot of time modifying it (see pic) but I still wasn't happy with it.
If you fit one of these you'll need to fit reversing lights to be legal, so you then have the problem of where to mount them.
 
Anyway, I finally decided that the stock Kouki center looked best so I refitted it, and I don't think I'll change it.