how far does your output stick out past the end of the case? I have a TH350 to 203 adapter but I don't know if it will work for you. My output sticks out 3/4" out of the end of the tranny. You can have it if it will work. I know the 700 and th350 have the same bolt pattern.
nevermind just read the above link and it shows you still have to replace the output to use a th350 adapter.