way back when I was in the 9th grade, (1971) there was a guy at my highschool who put a straight axle under a year old challenger r/t. car looked pretty cool back then. can't help you about putting one in, but look at some back issues of Hot Rod magazine. they had a bunch of straight axle cars in there within the last 6-8 months or so. good luck.
I helped stitch together a couple of chevelles and a 67 firebird in that gasser style look back in the early 80's. we used a dropped T front suspension out of an ancient 100-series ford van. it seemed to work pretty well although the firebird had a few issues due to poor welding and general design but overall they were fairly problem free (front suspension-wise at least).
love that old-school hotrod look. thats really the first time Ive seen that done on an A-body. I kinda like it.