Lovely looking bike, quality 90's mtb with slicks is the ultimate commuter bike, great on the roads, no need to worry about potholes or cobbles, more than capable of taking shortcuts across parks and fields, in fact the bike is happiest in those situations, as light as a hybrid, not much slower than a road bike but far more comfortable and robust, and bang for buck there's no debate, a few hundred quid spent wisely on the right bike will deliver exciting and comfy urban riding.I did exactly what you're thinking about doing with a 95 Pine Mountain and it weighs around 9.7 kg. I took off the granny ring and run it as a 2x8. The gearing of course will depend on you and the terrain you will be riding in. I live in a flat area and use only the large ring (42) and the smaller cogs on the rear. It's certainly fast, only a minute or so slower over 20 miles than my steel road bikes of similar age.
And I'm sorry for all you consoomers out there who simply must have the latest committee designed cookie cutter model - retro mtb's with slicks are cool as ****!