I would probably avoid that weber as the same amount of money can buy you a much better unit. Being a downdraught unit, it might not fit under the bonnet line.
http://freespace.virgin.net/tommy.sandham/weber.htm
You may end up needing to have it stick thru the bonnet like this
some other website wrote:
......The number refers to barrel diameter in mm. The DCD is a twin choke and is really referred to as a 28/36 DCD; the 28 being the primary barrel diameter, 36 being the secondary diameter.....
.....The 28/36 DCD on the other hand may be fitted to 4 or 6 cylinder engines BUT the unit is intended to supply ALL of the cylinders. The function of the two barrels is to provide a compomise between economy and performance. As you quite rightly pointed out, the second choke only opens when the demand from the thottle is high. In fact, the secondary choke does not open until the primary choke is 2/3 open.....
....The principle used to improve the economy with the DCD is directly related to the smaller barrel and hence smaller venturi. With a smaller venturi, better fuel atomisation is obtained when the air flow through the carb is small......
....With the DCD, the cold start device can effectively be considered as a separate carburettor.....