The National design used MN2488 and MP1620 BJT Darlington transistors as output devices -- unobtanium.  Good luck.  Newark Electronics has them as "Special Order" Items.  I suppose that you could use power darlingtons from On-Semi, Fairchild etc., I chose instead to use the Sanken SAP16N and SAP16P power Darlingtons which were obtained from Profusion in the U.K.  Profusion got the transistors to me in just a few days with their webstore and Royal Mail. 

Importantly, the Sanken devices with their built in temperature sensing diodes make it unnecessary to use a Vbe multiplier to prevent thermal runaway.  I lifted a leaf from the design in the Summer 2005 issue of Elektor which described an amplifier design using the Sanken devices and discrete transistors.  The circuit is shown below:

A 3-d rendering of the amplifier board is shown below (the printed circuit boards have not arrived yet.  You can see that I took pains to maintain star grounding.  No ground plane or shield plane are designed into the board.  There is a power stud at the junction of all the grounds used to connect to the power supply.

You can make the input connections at the interior Molex pin connectors OR you can use a  10uF input coupling capacitor and the outermost Molex connectors.  National indicates in their application note that the input coupling capacitor, or its absence, had the most dramatic impact on the sonic performance of the amplifier. 

Click on the above GIF for a larger and more clear image.

National recommends that you use 2 toroidal transformers and full wave bridges for the positive and negative supply rails and I won't quibble with them.  While I show 22,000uF electrolytics below, National used 27,000 in their demo and apparently used 16 gauge wire to make the power connections.  Consult the National Semiconductor Application Note for the details.