I would recommend that you register on
the 501st Legion Sith Lord Detatchment Home Page. They have a thread there dedicated to the Rubies Vader and what needs to be modified in order for it to be considered accurate. Here is what I could find:
Rubies Vader
To ROTS:
Helmet - needs to be replaced with an ROTS MR or equivalent OR modded to appear symmetrical and painted solid black
Chest armour - the Rubies is modelled on the ROTS armour but is on the lightweight side. It will not stand up to heavy trooping in the long term. Recommend reinforcement from underneath or replace with an alternate ROTS set. The Rubies needs to painted in the accurate colors and the shoulder pauldrons permanently fixed in place.
Chest box - needs to be modded as follows: 1. replace rods and coin slots with accurate metal pieces; 2. repaint box; and 3. light orientation must be reversed.
Belt and boxes - needs to be modded as follows: 1. repaint boxes and buckle; 2. replace foam belt with leather substitute; and 3. replace plastic knobs with metal reproductions.
Shins - modelled on ROTS shins; minimally passable if painted appropriately. Most replace these with a sturdier version.
Cloak - needs to be lined, hemmed to floor length, and an accurate chain added
Surcoat - passable as is, but most eventually upgrade
Bodysuit - passable as is, but is notoriously hot. Most upgrade this to leather or pleather
Codpiece - passable as is, most upgrade
Gloves - the Rubies gloves are not stitched accurately and will need to be replaced.
Good Luck!