You can still buy 1000 watt mogel base lamps.

[Linked Image from grainger.com]

Lamp,1000,1000 W
Incandescent Lamp, Wattage Rating 1000, Clear, Brass Base, Mogul Base, Lamp Designation 1000, Voltage 130, Lumens 23740, Rated Average Life 1000 Hours, Shape PS52, Maximum Overall Length 9.50 Inches, Diameter 6.50 Inches

This lamp claims 23740 Lumens that is very close to what a 400 watt metal halide lamp produces. [Linked Image]

Bob

Bob Badger
Construction & Maintenance Electrician
Massachusetts