Will Ferrell as Murdock? The Rock as BA? Luke Wilson or Jason Bateman as Faceman?
I see 21 Jump Street re-done as a drama instead of a spoof, like it looks like the Miami Vice movie will be. So I'd cast some up and comers that I haven't heard of.
Topher Grace as Ralph?
Magnum would be tough to cast, unless you were going all out comedy and then anyone who could pull of the Tigers hat and moustache would do. Maybe Paul Rudd or it could be a Sandler movie.
Vince Vaughn as Cody, Matt McConaughey as Nick and Justin Long as Murray. I'd suggest someone for Roboz, but he didn't talk in the series.
WilmerValderrama and Stiffler as Ponch and John?
Ben Stiller as the Fonz?
I'm sure it's inevitable. Suggest your cast member choices...