Go for it, just keep the original stuff around as sooner or later, the 1980s Japanese bikes will be pretty collectable IMHO. Aero levers and a good seat are logical upgrades.

I have thought several times about putting a set on my 1983 Lotus myself, as that is a common upgrade I do on keeper bikes. I probably will do it one of these days. My seat is not original of course. This bike was my favorite thrift store find.

Since this picture, I have also converted the crankset to a homemade compact double, by using a couple of spare chainrings I had on a mountain bike. My basic rule is that I will make any changes that make the bike more ridable for me, while not doing permanent irreversible damage to the bike. I figure most of these vintage bikes have already spent too much time hanging in the garage.