Well, not sure if dashboard for E23 and E28 is interchangeable. I saw quite a few E23 dashboard in one workshop in Puchong.
Meter for E28 should be available in junk yard but you need to search for it. I think the meter is interchangeable between E23 and E28 (auto to auto) so you might want to ask the junk yard on this.
I do have a spare VDO for E23 728i.