Revised update on Head Gasket cost
I misquoted the final price to machine my head & valve seats; replace the stem guides, valve seals & head gasket; and to replace the fused OE header/catalytic converter assembly with a stainless steel unit from TimeValve (w/ a modern cat and no pre-cat's). The total price was $2,600 (including parts) not $3,600. I saved a lot by buying parts through Phil at PartsShop -- listening to the advice in this forum (I did not replace the head -- wasn't necessary & it did not need to be welded [thanks for the concern Larry]) and developing a good relationship with my MB specialist mechanic. He cut 5 hours from his bill.
Regarding the drop in MPG -- you're right, it was completely due to my faster and more agressive driving. When I pretend to be a grandmother I get 19 to 20 mpg.
Thanks for all your help!
Restored & Rebuilt '87300E Obsidian Black, Palmino Interior, Euro Lights, new Bilsten HD's.