Case in point:

I am at 438 rwhp/413 RWTQ at .8 bar, SC heads with porting, stock manifold, 7.5:1, K27 HF turbo -- heavy track use

Those numbers are very encouraging. I will be very happy if I get anywhere around there. I know what my 3.6 feels like with 285 factory rated HP (dont know if the factory uses flywheel or rwhp for their numbers) so that much improvement over where it is right now would be all the power I would ever need in a 74 chasis.

My 3.6 is probably a little over the factory HP numbers since it has SSI's on it... but I suspect I will still be gaining ~35% HP over my current configuration so that should really do the job. Heck it is already sub 4 seconds 0 - 60 so with 35% more power it will be in the supercar performance range :)

Ironic - I had a Euro 1979 911SC with Varioram 3.6 that weighed 2450 lbs and had 280 at the wheels.
3.8 cams, B&B headers and Flowmaster exhaust, no catalysts, re-geared 915.
Car is a rocket - but the 930 even more so. 200 more lbs yet 158 more hp and scads more torque. :p
The current SC owner is transforming it into an early RS look-alike --

Are you trying this on a 74' tranny? I'd think you might consider one of the later stronger units. As Craig points out torque goes up even more and hits faster both contributing to transmission death. Brian has made it work but the power to break her is there when ever you feel rich.

The transmission in my car is out of an 86 with a LSD. However, I am looking at a short G50 conversion.