At least up to 100 mph, a 533i will run with a Euro 500SEL or US spec 560SEL.

Congrats on the acquisition, I love E28s. My parents ALMOST bought me a 1987 BMW 535iS (with sport suspension and bodywork and limited-slip diff) in my senior year of HS, but got the Volvo 740 Turbo because the BMW was "too fast and had a stick shift". Hey, that's why I liked it!

But anyway, post some pics of this new E28.

-Sam