I don't think the launch broke it, the clutchless shift did something to second.
Lots of higher HP V8 have run the 833 without problems.
Using a clutch.
If you look at the power path through a 833....
It comes in, drops down to the countershaft and then back up to the main.
Only thing that changes is each gear you select.
It's not going through each gear.
The Lenco has the additional gear boxes in neutral.
So as you make a shift and add a gear box the power loss is added till you get to the last gear box.
That is how I understand it.