Hi there! If you can drive one first! And see if you like it! I own three Cobras one original and two replicas and out of the three the Backdraft is the one I don't like! It feels really loose!
It's an earlier car though, their newer Cobras may be different not sure though!
As far as fitting a T56 Magnum on a Backdraft not sure it's possible without extensive modifications, mine has a Tremec 5 speed and it's touching the body on three locations not much room under there.
The other Cobra is from a company that no longer exists I believe they used to be called "SMC" but it was a solid car and I have done a lot of work to get it the way I want it! And it does have a T56 Magnum installed, and yes it's a heavy transmission! But it's bullet proof in my opinion. In my case I like the extra weight because of the power that car puts down. 690TQ 725hp at the wheels! If you like send me your email and I will send you pictures of the car and the underneath so you can see the T56 Magnum installed.
Nick1025@san.rr.com