I literally just finished putting an GM 8 lug D44 in the front of a dodge, I had to move the GM perch's out 1/2" on both sides to line up with the Dodge spring width. The Dodge spring perch's are 1" wider overall than the GM. And all measurements on both axles were taken from center. I spent weeks staring at it to figure out what to do with the right side perch because it is cast in the punkin.
Bowing the GM springs out 1/2", because the Dodge perch's are wider, will get it in there but it wont articulate like it should due to the added stress on the spring and you will go through bushings like crazy. I tried bowing my Dodge springs in to meet the GM width and it put the spring in such a bind by the time the u-bolt were torqued i could visibly see the distortion in the springs, shackles and bushings.
I searched like a mad man to find an offset something, anything to make it easier but there was nothing to put a GM into a Dodge, I do not know about going the other way, there might be something for that. My guess is the only thing for it will be an ample helping of elbow grease though.