By my reading of Weerninks book P140 all the 823 and the 2.8l 3B cars have the same valve timing just the bigger carburettor on the 3b squeezes another 9bhp out for the 2.5l and the 2.8l rounds up 140hp.
the timing is
in opens at 13 degrees BTDC ,closes at 57 degrees after BDC
ex opens at 57 degrees before BDC, closes 13degrees after TDC
Sketch 510I sht2 confirms this.
Clarkey