Isn't this a group 1 manifold for 44 IDFs?? Had a set back in the day. Made a huge performance change on my RS2000, but the carbs went out of balance by the end of the street.
EDIT. see http://www.capriracing.co.uk/forum/viewtopic.php?t=248
Mind you, this is an aftermarket IDF manifold, as mine took account of the angle of the engine, whereas these mount the carbs at the same angle as the engine.