The OE center replacement is hard rubber not glass. They get pretty spendy. There's one on eBay for 250$ or something crazy. I would stay away from the glass corners as well. I think the glass center would be better if it matched up ok. The OE has screw holes.
Not a bad idea, I would. I'll sell mine for FOR $199.95 http://www.ebay.com/itm/NOS-Origina...ash=item58e917c40a:g:t14AAOSw4GVYPggt&vxp=mtr http://www.ebay.com/itm/1974-77-Che...ash=item1c787e9598:g:dyMAAOSwux5YMchA&vxp=mtr
I ended up removing mine because it would get damaged by parking markers and road dips and haven't missed it.