When I had mine rebuild/ported polished I was told it had 35mm inlets and 29.5mm exhaust valves. When it got home I measured them and they were what I was told. Which I thought was strange as......... According to the R32 engine manual:
R32 RB26 - 35mm inlet, 30mm exhaust.
R32 RB25DE - 34mm inlet, 29mm on the exhaust.
I remember one measured his r33 rb25det valves and they came up as 34mm inlet and 29.5mm exhaust, I've measured an rb26 head that had 35mm inlet, 29.5mm exhaust yet another bloke has measured his rb26 head and told me they were 34.5mm inlet and 30mm exhaust.
There does seem to be a little variance. Probably just the tools used. A poor tradesman always blames his tools. lol