well not really knowing the different between c4/c6/c9 etc i thought they were basically the same box
anyway, i got an email back from wholesale automatics which reads:
Rodney here from Wholesale Automatics.
I wouldn't use a C6 as they are not a good drag racing transmission. The
best transmission to use is the smaller C9 transmission that when built
correctly can handle quite a lot of power. We also use these transmission
with the V8 Engines.
The C9 will also bolt straight up to the 250 6cyl.
You can build them as either a full manual of a semi auto. You can fit any
of the B&M or Hurst range of T.bar kits. We find the B&M Quick Silver to be
a more reliable and very stronge unit.
We can built that as a 450Hp unit or a 650Hp unit.
No warranty on any transmission used for drag racing however we are
approachable.
Extreme Full Manual 650 Hp Stage III Outright C9 with Hi Tuff Input Shaft,
Cast Aluminium Sump, 4 Pin Chrome Molly Front Planetary, Keas Valve Body and
6cly bell housing is $3275 inc gst Outright.
Hi Stall Torque Convertor is extra depending on the stall speed.
Hope this helps.
Kind Regards
Rodney
Wholesale Automatic Transmissions
Factory 1/58 Barry St
Bayswater
Victoria 3153
Phone: 03-97628004
Now after going off what you said gassed, that price sounds a lot better than the possible cheap and nasty