Is the 200 4R strong enough?

Yesterday I asked about gear vendors and got some really good input. Only thing I worry about is the added room need under the floor area that it needs. I'm looking at the 2004r FROM Monster transmissions. My question is , some people have told me that this tranny is not strong. I'm running a 70 Impala with a 383, withe about 410hp and about the same torque. I have 3:55 gears and currently a th 350. The main reason I like this tranny is because of the almost exact swap. I want to do the install myself. Anybody running one of these that can give me any input. Thanks in advance, Trainor Here is a link to the Monster tranny. 200-4R Transmission Remanufactured Heavy Duty Performance