hi thomas.
I think the car you are looking at would be an earlier jh classics model. Deon was born out of jh a lot later- possibly early 90's I think. Although deon did fit the ford v6 engine to the gt this may suggest the date 1979 is wrong.
As to the dash I'm sure these can still be sourced as can most of the dials etc.
Price is a big thing though.I have seen pristine examples go for around 20 to 30 thousand pounds-but of late this seems to have come down.A couple in kit car mags can be had for a little over 16 thousand pounds-while on ebay they seem to go for around 10 to 12 thousand for a finished runner and around 7 to 9 thousand for one requiring work. (don't know what these work out in euros)
ian