Scarlet Mail Set

The Scarlet mail set which still drops in the Scarlet Monastery instances were iconic for someone who leveled a Hunter or Shaman before Heirlooms. Even though the items had Strength, many people took these as upgrades from their leather to mail gear as they hit level 40.

Hunter

Chain of the Scarlet Crusade
Blood Knight War Helm
Splintermark

Shaman

Chain of the Scarlet Crusade
Fel Iron Hatchet
Raging Berserker's Helm

High Inquisitor Whitemane

This is the closest I could get to the Scarlet Monastery boss, the Glowing Brightwood Staff is a world BOE drop, so if you are unable to pick that one up there are other options, just in a slightly different colour, like the Guiding Stave of Wisdom.

Whitemane's Chapeau
Cindercloth Pants
Crimson Silk Shoulders
Fire Striders
Cindercloth Vest
Sash of the Burning Heart
Sunfire Handwraps

Scarlet for Plate

The Scarlet Crusade have an item set (Chain of the Scarlet Crusade) that drops in the Scarlet Monastery, however these items are mail and due to the restrictions of transmogrification can not be used by plate wearers.

The Scarlet Tabard is the most important part of this, and can be looted off the Scarlet Trainees which appear after Herod is killed in the Armory, however it has a low drop rate so a little bit of farming may be in order.

Ragesteel Helm
Darksoul Shoulders
Ragesteel Shoulders
Darksoul Breastplate
Khorium Belt
Ragesteel Gloves
Darksoul Leggings
Khorium Boots
Ravager
Aegis of the Scarlet Commander
Ironspine's Fist