Thanks guys for the welcome. Blame Mike and Edd's (wheeler dealers) caterham for the ideas. The astra has keyless entry and start, obviously can't use the entry bit as no doors but the start button I can definitely use. It's only basic cruise control and astra vxrs are being broken daily now so parts are cheap for the power. And hopefully it will feel a bit more modern inside as I feel the sierra has a dated look and feel now.
Astra vxr powered Roadster in progress