I've done several of these upgrades for friends and everyone has been happy with the results. This mod will turn out the street light in front of my house.
Host:
1) M*g 4D with 4 D cell alkalines = 6V
2) M*g 3D with 4 C cell alkalines = 6V
Bulb:
CL 606 (Carley 3 cell, 3.7v, 1.7A, 95 lumens.) $3.11
Pushed to 6v, bulb output, theoretical, = 517 lumens
3) optional - smooth out the beam with a LOP reflector, $20
4) optional - add a UCL lens, $7