Your work on this is quite commendable (would be easier to read in excel format).
I would like to add two highly recommended P-car shops in northern Illinois.
My fav: Perfect Power - Sol Snyderman
1009 Commerce Dr
Buffalo Grove IL 847-465-8837
www.perfectpowerinc.com/
and: Fischer Motors - Peter & Rick Fischer
908 S Northwest Hwy
Barrington IL 847-304-8822
Both these shops are highly qualified Porsche specialists (and other german cars)
and handle both street and serious race prep. Sol built my '73 911 vintage track car.