Not exactly sure what I'm going to do with it. Had intended to use the groupset on another bike and sell/resto-mod the frame, but also have a virtually NOS 600 SIS RD and shifters, so may just upgrade this and use it as a Sunday Ride With The Wife bike.
What you do with it is your business, but don't sell the bike short. Tune it up, make sure the brake pads and tires are still good and replace if necessary, and take it out on your normal rides. Unless you have a lot of hills where the 42t small ring won't be much help, you'll find you'll maintain the same speeds you do on your other bikes. A lot of us have upgraded these to current (or recent) drivetrains - I've got nine speed Tiagra 4500 compact crank, brifters and FD, with an Ultegra 6500 RD, on my '87; found a set of used 600 hubs and re-built the original rear wheel with the 600 hub and current freehub, and that bike is slicker than snot on a doorknob.
Then again, if the Mrs. is a Cat 2, your original plan would work fine!