Restoration of a suite of gauges costs anywhere from $650 to $1000. For the same price, one can also purchase new gauges of modern manufacture, if you desire a new look, or just want something different. Many new gauge sets are programable to suit many installations.
An early metal dash is simple to restore. They were merely painted with wrinkle-paint. One can either use the same process, which is simple to do, but finicky about application times and drying temperature, or go the modern route and employ wrinkle-finish powder-coating, which also makes proper application someone else's responsibility.
Later, plastic covered dashes are a good deal more work, since about all that one can do is to replace the entire cover, a 4-5 hour job.
The MGOC offers leather-covered consoles for the metal-dashed cars, which can be modified to work with the padded US dash with careful trimming. In leather to match MGOC seat kits, for £239.