C body 727 into A body. Any Issues?

I'm putting a 440/727 into a 70 Duster. The car has the original slant six K frame and I'm usung Schumacher mounts and headers. I have two 727 transmissions. One is from a 74 Imperial 440 and the other is from a 72 Newport 400. My questions are; Is either of these trans cores better than the other as far as strength? Which ever one I use will get a rebuild so I'm wondering if one is better than the other to start with. They appear identical except the Imperial trans has a weight bolted onto the very rear of the tail housing and also the front pump casting is slightly different between the two. The tail housing is quite long, is that a problem? Obviously I need a shorter driveshaft but I want to know is there any other problems to be aware of? Thanks for any info, so far everyones been very helpful and I appreciate it.