How much horsepower and torque can a 700-R4 tranny handle?
I've got the later model version which i think is a little bit stronger than the earlier versions.

 

It all depends on what you do to them. Which upgrades?, valve body kit?, etc. I have the parts you need to do this right the first time if you plan on rebuilding it yourself. With the right parts & torque converter it can handle about 525-550 HP max. If you need it to take more then you will need the HD input drum ($250.00), this will give an additional 75-100 HP to the max. rating. I hope this helps some.