I build the TH400 for Street/Strip Pontiacs. I can build a best-of-parts TH400:
Best [121 or 895] Front Pump,
Best Forward pack,
Best Direct Pack & Sprag,
Best Center Support design,
New Alto Red and Original Borg-Warner radial-groove Clutches.
Best 1-2 Planetary sets and can use the 1965 GM THD 34 Element Lo-Roller Sprag if desired.
Best GM Armasteel Tailshaft with GM Reinforced Tail Cup.
Best [AH] valvebody with careful programming.
Generic GM separator plate having the 1969 428HO "Tow Package" program.
Full Direct Pack fluid fill for Highest capacity 2-3 3-2.
Best unmodified GM Govenors for automatic 1/4mile upshift.
Best Case prep and hardware selection: and will get it to nearly concourse quality if desired.
I can do this because I'm not a Business. That means I can keep the best parts laying around. you also get a scoresheet of the internal setup. All the Parts, and valvebody settings for your (and my) Reference. Good to low 10's for many many years.
You can watch and be taught as the build occurs.
Converter will be the weakest link and we can talk about the tradeoff there. Final note: I'm probable the lowest price. Shipping free 'cause you pick it up.
Email me if interested.
The 68GTO Project has a Switch-Pitch TH400 that ought to handle 10's. Thus far it works well up-n-down the driveway, and no leaks. Signature data below all ran through my TH400 recipe I or recipe II.
HIS