5000CSQT head mods...

[ScottyCBoy@aol.com]

HELP!!!

     I was peering in the depths of the engine compartment on my baby, a 1987
5000CS turbo Q with 158k.... And I discovered the origins of an exhaust leak.
 the manifold has a couple of broke studs and a rather large crack...  I plan
to replace the above items aith a two piece Audi manifold and K24 turbo and
If I need to pull the head to have studs drilled I was going to use that as
an excuse to do some head mods....  The questions I have are:  

Is there a performance gain/loss from using a latter model Closed chamber
head on a turbo car???  
If bigger valves are going to be installed what is the largest head diameter
for intake/exhaust???
As far as porting goes where can the largest gains be made, the intake ports
or the exhaust ports???
What kind of cams are there to improve low end torque??

Thanks,
Scotty