Today I followed the steps provided here by azTony and all went well, same part #, cloth seats manual. I used zip-ties instead of hog rings when buttoning things back up, which worked like a charm. Also stuck a 3.5" length of Gorilla tape onto the factory reinforcement cut-out section underneath the cushion for additional reinforcement. Tomorrow, will bolt the seat back in and see how it feels down the road. I'm certain that my back will benefit from replacing the 25-year old cushion. This was the plan A option; if improvement is not significant enough, drastic action could follow, as in $cheel-mann aftermarket seats.
Thank you for reviving this thread. I am completely inspired to replace my foam now. I don't know why it took reading this to make me realise it is definitely a "thing needing to be done"