chrismetallica1 posted nice photos of his Remington 870 with long barrel and different upgrades:

Remington 870 - Standard

Remington 870 - Standard

Remington 870 with Two Mesa Tactical Sidesaddles

Remington 870 with Two Mesa Tactical Sidesaddles

Remington 870 with Magpul Furniture

Remington 870 with Magpul Furniture

Remington 870 Magpul Furniture Stock Forend

Remington 870 Magpul Furniture Stock Forend

Remington 870 Magazine Cap

Remington 870 Magazine Cap

Remington 870 Trijicon Tritium XS Big Dot

Remington 870 Trijicon Tritium XS Big Dot

Remington 870 Trijicon Tritium XS Big Dot

Remington 870 Trijicon Tritium XS Big Dot

Remington 870 Trijicon Tritium XS Big Dot

Remington 870 Trijicon Tritium XS Big Dot

Recommended Product:
XS Big Dot Tritium Sights

XS Big Dot Tritium Sights

You can get XS Big Dot Tritium Front Sight on Brownells
Mesa Tactical Sureshell Holder

Mesa Tactical Sureshell Holder

Get Mesa Tactical Sureshell Holder on Brownells
Magpul Remington 870 Stock and forend

Magpul Remington 870 Stock and forend

You can get Magpul Remington 870 Stock and forend on Brownells