Originally Posted by squirtdad

if you order from england you can get a complete deore 610 groupset for $260 Shimano Deore 610/615 Groupset - Mountain Bike Groupsets - Ribble Cycles

this way everything is matching and works together.

need to verify that the rotors and cassette would work with your wheelset

Another thing to think about...... the redline was a pretty entry level model, it might be more cost and anti-frustration effective to just buy a new bike.