I burned up 3 stock 727's behing a basically stock 340 when I first started driving. A shift kit made a world of difference and a good valve body was be better.

I've run a 904 behind my 360 Dart Sport. JW Transmissions builds them with nothing I'd consider trick -

* Manual reverse valve body
* 4.2 kickdown lever
* I believe the "red" clutches, not sure about bands.
* Amsoil Supershift trans fluid
* Trans cooler and deep pan
* Converter flashes over 5,000

I'm pretty sure the rest are OEM parts except with some oiling/bearing tweaks.

I weigh 3,540 lbs +, have run 11.22 @ 116 with 1.47 60' times. On several occasions after several years of running, my trans builder said to keep doing whatever I'm doing as far as running it, adjustments, fluids, servicing, etc. The only time I remember that a 904 went "BOOM" on me was when a rear u-joint let go at the 1/8 mile mark. The result ended up with a bent converter and chunks taken out of the block. But it wasn't the transmission's fault. I got a steel billet rear end yoke and solid Spicer 7260 joints that are still in after many years.

Get the proper B&M flexplate which will solve the converter balance problem and it's a heck of a lot more durable than the OEM plate.