Thoughts on a short term trans behind healthy torque, a 2004R or TH350?

[Olds 307 and 403]

As I move closer to building my 424 SBO, the motor itself doesn't bother me as much as the trans and rear. I know the motor will be 400+ HP and 500 ft/lbs. My long term goal to lay down the hammer on all but the highest power modern muscle cars is a beefed up 2004R with billet parts and 3.90 gears and posi in the Type O in my 70S. Gear multiplication is a huge reason modern cars are so fast, I need at least 4 gears and OD to compete. Currently it has a 2.78 open ratio along with 28" tall tires means a liveable 2250 at 60 mph. I have a good shifting stock 2004R with a deep pan and a 2300 stall about the minimum I would run, should stall a bit higher with more power. Will a CK billet servo and shift kit help this trans live more than a day? I not sure if the Transgo shift helped much but on the one, the converter imploded and the other I set the band too tight with the Billet servo. The last 2004R was ran low due to a crappy, leaky Hughes pan and a rolled dipstick seal. Still have that trans for available parts and can get more cores. I can also get a used BOP TH350 from the same wrecker. How much power would a good used TH350 take with a Transgo shift kit? I don't want to go the TH400 route, too much modification. I am not a fan of TH350 stock, saw two fail behind 165 HP of mid 70's Olds 350 power, one had 158,000 miles. I also saw one last about a day behind a stock mid 70's 454 truck motor dropped in a Camaro. He through a used one in with shift kit, lived for a while at least. Is the TH350 with a Transgo kit the way to go short term? I would also throw in a Jegs 2300 to 2700 stall converter. I have a governor for both trans that are better than the stock 4000 rpm shifts, well 3000 on the current 2004R. I am not a TH350 fan, so other than inconvenience, I don't care if it breaks. Does it have a better chance of living than the 2004R? Thoughts?

 

[Rocketman269V]

I have the T-350 from, Turbo Action, that we ran in our Stock Eliminator car. It has a 2.75 1st gear, all light weight components, and is built to handle over 400 hp. We had this behind our '70 W-31 350, that went 11.84 @ 112+ in a 3600# car. It is physically lighter than a stock 350; we had to add weight to the car to make minimum for tech. It does have a governor, for automatic 1-2 shifts. The only thing that you would have to be careful of is backing up; there is only one clutch plate in reverse. The only reason that we removed it was to go with a Metric 200, when NHRA changed the rules. That trans has even less drag.

 

[Olds 307 and 403]

I am probably going to do the 2004R. Being an 86 it should have the hardened sun shell so that might get by. I will do a billet foward drum with a welded on shaft, CK shift kit and servo along with their pump. Last pump I did, I struggled to hit 220, their reman pump should hit 295. I will know the condition of frictions transferring over to the billet foward drum when I transfer over. This trans was rebuilt, just how long ago and what parts were used is the issue.