Was it an Aspen R/T or a Plymouth Volare road runner? It couldn't be both, unless someone else added the Plymouth-only decals.
Sad to say, if it had rot in the floorpan in the early '90s, the LH front frame rail probably collapsed long ago. That's the reality of F/M/J-bodies--they rot on the inside edge of the rail, facing the transmission. Because of the sentimental value, to you a repair like that might be worth the expense, but to most it would not be. I really hope you find it, but I suspect it was junked years ago. That being said, it might be worth your while to call boneyards around that area, asking for the longest-term member of the staff and seeing if maybe someone recalls it, or maybe it's still sitting out in their yard.