Welcome to the forum, Leadfootin. I think we'd all love to see photos of your Plus 8 and the engine. I can't really help with the choice of rims. But companies like in the link below can build you custom rims for central locking or bolt on. This company Image Wheels has also built rims for the Morgan Motor Company as original equipment, e.g. for the BMW Plus 8 Speedster.
https://www.imagewheels.co.uk/
