I would bet that most of the US e30s had sunroofs.
A glass sunroof definitely has to be replaced (or completely taped over, but you’ll make more money selling the glass sunroof) - you can either find a stock metal sunroof and install it, or fabricate a metal plug or skin (same material as the roof).
Welcome to spec e30 building!
cheers,
bruce
7.13. Sunroof clips
7.13.1. Sunroof clips are recommended, but not required.
7.13.2. Glass roof tops shall be removed or completely taped over. Use of clear tape is recommended.
9.3.13.25. The sunroof cassette mechanism may be removed so long as a replacement panel is either securely sealed (welded/bonded) or secured in place with retaining clips as specified in the CCR.
9.3.13.25.1. The panel shall be flush with the roofline and of the same material as original.