RE the various dust cap mods, it should be noted that the aluminum dome is responsible for dumping a lot of heat from the voice coil (aim an IR thermometer at them in use for proof). I've temporarily painted them with liquid vinyl like GM suggested to tone them down a bit for blues guitar, but OG's 4" paper dust caps probably have less thermal effect (screen-vented from 416 should be best).

Right about the 8HII being the highest power rated, when they came out, Altec offered a lifetime guarantee... unheard of in the MI world.