Simplest is a set of bar-end shifters, any old ones and simply select friction. The amount of pull per click in 7s is sufficiently big that it generally shifts cleanly.
I had forgotten about the Tourney ones. The Claris 8s are reportedly pretty good, although triples are rare.
A full Campag 8s...
There is only a single 7s brifter type, which are RX100.
Alternatively early Sora existed in 7s, but with the Campag ergo-style thumb lever on the inside.
I believe Microshift do some now, not sure if there is a triple option.
I think that the extra loading from the brake means that the fork has to be beefed up towards the tip - so no triple butting for discs.
IIRC the fork like the one pictured above is longer (440mm perhaps?)
I did it for three years while living in Singapore. But their public transport is integrated and wonderful. I cycle commuted daily in 32C and 90%+ humidity. There was never a need for a rain jacket, I was soaked regardless of the weather.
UK public transport and cycling facilities are...
The Carrera around £20 as super-cheap transport (no need to lock it as it's so horrible) or alternatively as an anchor.
The Fisher is a little nicer, but it's essentially a 25 year old lower mid-range bike. It would make a respectable commuter for £50.
Schwalbe Marathon Greenguard are tough and reasonably priced at around £20 each, especially considering that they are surprisingly excellent performers for rolling resistance. I have run them for years on my tourer.
Campag and Shimano have identical 7s spacing at 5.0mm. I happily ran a Campag 7 setup on a Shimano hub and cassette.
Campag continues the 5mm spacing into 8s whereas Shimano squeezed it down to 4.8mm, which sort-of works with a Campag 7/8 setup, in the same way that the 7s Shimano thumbie with...