After doing some research it seems a good combo is the 9a block with the ABF head. The 9a block is normal height so no clearance problems if I decide to fit the fuel injection off the Seat and the ABF head has the following advantages over the 9a head:
Small 27mm dia exhaust valve on 27mm seat for improved flow of hot exhaust gas
Cooling passages in the exhaust port to reduce hot spots and improve durability
Cooling channels in inlet port to improve/vaporisation and wall warm up.
Cooling passages in the combustion chamber to reduce hot spots and improve durability.
Improved squish areas working with revised piston.
Optimised valve shrouding on the inlet toward spark plug hole
optimised head shape around the shrouded part of the exhaust valves.
Reduce valve guide protrusion.
Reduction in port casting imperfections.
In/Ex Port flow improved over "51***373" heads.
Late model 9a motors had the same head casting numbers as the ABF motors so there shouldn't be any problems fitting the ABF head. The only difference was the inlet and exhaust cams.
http://www.vwwatercooled.com.au/foru.../9AvsABF-1.jpg
This is the bit that convinced me to use the ABF head. It develops more power and it has a similar torque curve to the 9a so running the wilder ABF cams isn't going to kill my low down torque.
http://www.vwwatercooled.com.au/foru...FVWplot1-1.jpg
Lots of info here.
A VW 16v camshaft study.