I don't think it's silly, at all.
You should just arrange all that stuff in whatever way makes you feel happy.
I can understand why you'd want to retain the Sansui; that's a pretty piece.
Personally, I rather like music in multichannel and also enjoy the Dolby surround effects present in a growing number of modern TV series (as delivered to me via DTV and decoded by my Onkyo 805). So, if I were in your shoes, I'd probably have an itch to see what M50's as L/R and an M3 as a center sounds like.
You can get pretty nice deals on Onkyo refurbs at Accessories4less and shoponkyo.
Most important thing is to have fun and enjoy the time you have with what you've got.
