I need help....Please advise

Hi all,
I bought a slant six 904 tranny not knowing the difference from a slant six 904 and a 318 904 (the starter mount on bell housing) so I had all the guts swapped out of the slant six 904 into my 318 904 tranny. I also used the slant six torque converter in my 318 904 is that a problem???? Does the 318 motor need a 318 converter????? The darn thing leaks tranny fluid and after inspecting the bell housing dust cover there is fluid up in there. I'm trying to do process of elimination and find out if it’s ok to use the slant six converter in the V8, if it's not the converter then the front seal must have got pinched during tranny installation. Please give me your thoughts. The car is a 1973 Dart Swinger with a 318 - 904 tranny

Thanks
Rob