I belive the 1473cc's really need bigger valves, both exhaust and inlet. Thats why I'm going 38/33, but 37/32 might be more reliable.
On the 1473's, I think you also are on the edge of what the 3F manifold can do well.
I'm fairly sure my 1473 will sport a different plenum 
are you going turbo? this will be rather interesting 
should start a thread on it
like people say, just dont think there is enough research into the 1473cc i bet there was a shed load of trial and error in the 1341 when people first started doing it
1341 is probably the limit on other things as you say valve size, inlet mani size etc
The basic spec is as following
1W block
JE 77mm 8,5:1 cr
Knobloch Sport 38/33 BVH (I think I have posted some pics here)
Rothe exhaust manifold
PSD Intercooler
PSD downpipe
For starters I will use a GT cam, K03 turbo and 3F manifold and early PSD 49.5 mm TB
When I have mapped it ok, I will change to either a K04-15 or a Frankenturbo type turbo and try to have plenum made up with sufficiently large volume. The cam will certainly be better than the one I have now, but I think I can get away with at least the same duration and a bit more lift. The mildest lobe on some of the PSD cams are 276 degrees
For the 38/33 mm valve combo to work, you need need offset valve guides. I also belive the bigger bore helps the head "live", more surfarce are for the heat to "cling" to, for the lack of better technical words
