Bad tune, or engine at its limit?

[90Vette]

Last month, I took my '90 Corvette to the drag strip for the first time (if pertinent, it has a 1227727 ECM and runs $8D). I've been swapping parts bit-by-bit, and I've reached a pretty respectable combo:

• 383ci
• 9.3:1 SCR (8.4:1 DCR)
• AFR 190 heads (the old-school ones from before the Eliminators)
• Lunati 211/219 @ .050" cam (small, I know, but I didn't want to risk failing smog)
• 1.6:1 roller rockers
• Super-Ram plenum and runners
• Edelbrock High-Flo intake base, gasket-matched on the head side
• Hooker Elite 1 5/8" long-tube headers
• Accel 33.3 lb/hr (advertised as 36) injectors
• 58mm Holley throttle body
• 3" front Y-pipe
• Corsa cat-back

I've never had it on a dyno, and I've done 100% of the tuning. It would have been cheaper and easier to pay to have it dyno-tuned, but I wanted to learn to do it myself. I finished the header install just hours before I went to the strip, so I didn't have as long as I would have liked to nail down the tune. That said, the timing shouldn't have needed much tweaking, and by the end of my tweaking my wideband was showing lambdas of around 0.85-0.88 (12.5-13:1 AFR) at WOT.

While it was a blast at the strip, my highest trap speed was just 106.23 MPH. According to an online calc, that corresponds to 322.38HP. Even taking into account a 20% drivetrain loss (which I've heard is accurate for the ZF6 transmission), I'm barely breaking 400HP at the crank. Based on what I've read, that seems pretty weak for a built 383. Granted, my static compression ratio is a little low, but with such a small cam my DCR is already at the limit for pump gas.

Do you think my combo just at its limit, or does my tune need work?

Here are my relevant tables: spark advance, VE lower, VE upper, and PE enrichment and spark advance (if you're not familiar, it adds in the fuel and timing in those tables when I step on it). I've also attached a datalog (not from the strip, but it has some WOT) if you feel so inclined to look at that.
SR34 Timing.PNGSR34 VE Lower.PNGSR34 VE Upper.PNGSR34 PE.PNG