I just did an 80's cake last week. All I did was use neon colors and # 1M tip to make large ruffle shells around the two tiers. Ruffles were big back then.
If I could have, I would have made a octagon shape bottom tier and printed edible image of popular movies such as Better off dead (BTW one of my all time favorite movies
, sixteen candles, Farris Bullers day off, Pretty in pink, Footloose, breakfast club...well you get the idea.
If you want it to be more rock band you could do the same with popular rock bands back then. Madonna, Guns N roses, Skid Row, Heart, Kiss, poison, cyndi Lauper, ect...
Here is a pic. of my cake so you can get the idea of the color combo. Hope that helps.