I'm going to conditionally believe Taylor on this, with a few conditions -
#315 x 10 - 12 will usually equal out to around #405 for a single, which isn't too far off his claimed max.
The guy's #235 and been hardcore on for a few years now.
I'd also bet that the reps are 3/4ers or similar, and the #400 + is gym lift good, but not powerlifting meet good, so it could be possible.
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I'm not sure about the Smith to free bar conversion, but I figure #365 should make it comparable. I'd also let it go if all the reps were at atleast 80% Range of Motion.