soapstar,
Your Uno looks great doesn't it!
I like the wheels and the 'clean' look in silver with the colour-coded mirrors. Looks nice and straight and rust-free. When I had an Uno 60, I painted the instrument cluster top like that as well... Even that wiper has its practicalities (it's sometimes a little irritating having it in front of the driver) though I hope there's Rain-X on the rear window!
I don't really like that front grille, but then I would say that wouldn't I, as it is the obvious thing that stands out as 'different' and I like the original. That grille gives me the impression of being a piece of 12mm MDF with a hole routered in it. It would look better with more 'depth' IMHO.
Now, the misfire...
Mine's still on the original distributor cap I think, unless it's cracked they don't really wear out apart from the carbon brush which should probably stick out 4mm or so. What do the plugs and leads look like? Mine's still on the original leads

Maybe run the engine at night and look for flashes... and try a new set of spark plugs since the original change interval was quoted as 7,500km in the handbook (4,660 miles).
And about the turbo. I think that Mazda Familias and Subaru Legacies use a similar IHI turbo, but you probably need to match up several parts (different compressor wheels etc.) to create something that works well. It won't be a question of taking one off a larger engine and bolting it straight on; well it can be, but you'd lose driveability and economy.
-Alex