All fair comment, but apart from presumably being a racing rather than touring geometry, and presumably a low grade steel rather than 531 frame it was designed be ridden on the road and people did not make too much of a fuss about brakes in the 1980s. Quite valid comment about the suicide bars, but unless they get in the way of your hands, some people say they do, just ignore them. Just do not expect them to stop the bike, for obvious reasons.
Steel rims probably indicate a lower quality wheel, but assuming the spoke tensions are OK it should still last a long time. If a spoke breaks you put another one in.
As you have the bike I suggest trying it out in the configuration you want to use it, probably you have some hills to hand and rain seems to be in plentiful supply at the moment, so you can see what the brakes are like, whether it fits and is a comfortable ride, and what the gearing is like. the existing tyres will no doubt be up to this.
It is not necessarily difficult to change a double for a triple on a 1980s bike, I have done three. The first step is to loosen the adjuster screws to see how far the front derailleur will actually move. Then preferably find a cheap alloy triple that will fit the same crank axle length.
27 x 11/4 tyres are quite easy to find in the UK, in fact 27 x 11/8 can be got from Spa Cycles. The main tyre question is whether you need a spare in case of damaging one, because it is not a size used on the continent. I think you can assume that you will not wear them out. The existing tyres could be taken as spares.
The main thing I would consider with an unused 1980s bike is to check the bearings, in case the grease has dried up. However, if this bike is basically unused it ought to be in generally better condition than any second hand bike.
WJH