Bit of both. Get some pics of the original parts to see what the condition is. If the mufflers are rusty and the alloy parts are oxidized, it will indicate the heated garage may be exaggerated.
Looking at the condition of the gauges, (speedometer reading 900 Miles), especially the lettering decal on the tower, (really good as that will rub off when cleaning the lens), handle bars and general condition the bike looks real good. In fact better than good it does look like its in excellent condition. As for a clean up restore or a bike looked after sitting in a heated shed it is hard to tell. Improvements, especially the carbs is definatly a good. 2 into 1 well, the muffler looks loud and the headers are a preference over what would/could be considered better. changes the power band higher in the revs. Cam end caps and charging side cover inspection plate are aftermarket.
Doesn't mention brake hoses. if they are original they probably need to be replaced. They laminate with age. Rebuilt the brakes so the fluid should have been changed.........worth a question
Price wise, its your choice. many will say its to much and they can be got cheaper............ Low miles and with the upgrades and new tyres and road ready it's up to you what it is worth. If it is tagged for the road it would still be a negotiation on price. If you have to register it then the price is way to high and in my opinion, i would be taking that cost off the price and then haggle.........an 80SG seat is a + in my book comfy and can slide around on it when the bum gets numb or to change position.
As with any old bike there will be on going maintenance but where it has been stored will mean it shouldn't have to much t go wrong with it. Teething issues could be wiring connections that have been sitting for a long time. Maybe a thing to go through the whole loom and disconnect all connections and couplings to look for any oxidization and clean and replace if necessary....test the charging system, (rotor), for output, if the windings are a nice brown colour that would indicate little use and should be in good condition.