I take it this must be on extremely low boost? Somewhere in the 5-6 PSI range? Are you running a custom tune?
Also, I didn't happen to see any of your previous dyno runs, but don't LT1's usually put down 400+ HP/TQ bone stock?
Most of my knowledge and experience comes from the 5.0 Coyote, so I'm used to seeing much higher numbers...not that these are anything to scoff at. Especially if this is low boost...
Either way, from the pictures I've seen, it looks like a great fit in there. How was the install? Time, cutting/trimming, etc? Looks good.