Well to be simple
Aquarium Gardens
Twinstar 600 E - as tank is 50cm wide, you'll need to choose your plants carefully (no linear array LED or single T5 tube will provide even light across this distance), you can easily add a second 600 E at a later date if wanted
Twinstar 600 S - you can see how well this works on the Aquascaper 600 (60 cm x 50cm footprint) in George Farmer videos & AG display tanks, it will likely grow anything you would want but you'd (likely) need to add in the dimmer for non-CO2
Chat with Dave about fitting the light as tank is 75cm long
Go Chihiros if you're not fussed about build quality (or fast customer service)
It seem more complex then expected just for a light with no co2
Not really, just easier to recommend something if you had given more of an idea of your preferences
LED vs T5?
If LED, is RGB important to you? (better to buy a light once that suits, then end up dissatisfied with the esthetics)
Open foreground or dense planting front to back?
etc
& then you mentioned you might want to add CO2 ...