Hi,  I used to have a 1974 Datsun 260z that i raced in C Production in 1975 & 1976.  You had asked whether they used triple Webers.  Yes i did.  I converted from two 2SU-type 2 barrels over to three Weber 2 barrels along with a full race cam among many other things.  My 260z went from a car with some pep to a very very quick squirrelly monster!!  Top speed was 165 mph.