Thanks Gentlemen....it does, indeed, seem that the 1979 regs are not really available....however, the car did compete in a few rounds of the 1980 BSCC.....and these regs are (as you say Louis) printed in the Blue Book.
We'll therefore build the car to these, they were probably pretty much the same anyway.
We did track down a full set of 1980 regs (together with amendments) before they got into the Blue Book, and this is the first page. It maybe of interest.