87 190E 2.6 burns a LOT of oil

Hello all,

I recently purchased an 87 190E 2.6 (M103 engine), which is known
for having problems with oil consumption due to valve guide and
valve guide seal wear. Mine burns a lot. I purchased the car with
140k miles and I have all of the service records. Upon buying the car, I changed all the fluids to synthetics. Here's what I have found:

Driving around town: 1qt/600-700 miles.
Driving 80mph on freeway: 1qt/300-400 miles.

Ouch. There is no visible smoke from the exhaust. There are no oil leaks (garage floor is dry). Smog test passes, but is very high in the hydrocarbon department.

I guess I should fix this, probably by replacing the valve guides and seals. I would any advice - here are some questions:

Can I be pretty sure this is a problem with the valve guides/seals?
As long as the head is off, what else should I fix?
Does anyone have good advice from experience with this?
Does anyone know of a good mercedes mechanic in the Southern California area?

All help/advice/sympathy is appreciated! Thanks so much!

John