Purchase any chinese brand 70cc bike. Preferablysuper Power. Unique or Star. Spend around 3 to 4k on that and you are good to go. Replace both tyres with 6 ply rating tyres. Replace the wheel spokes with the ones used in CG 125 tyres.
Replace the headlight with an LED one. And if you want a bit more power, replace the carburettor with a cg 125 carb. Andreplace the chain sprokets with 15 38 size. 15 front and 38 rear. This is more than enough for speed. Power and economy.
I have done all these modifications to my super power sp70 since 3 yeas and I am quite happy. Never gave me trouble. Runs very fast on long route. Touches 120km/h without any vibration. Off course it takes time to reach 120. Its trouble free for me Alhamdulillah.
My bike gives a mileage of around 42 - 45 km per liter.
Planned many times to sale it and buy a used 125 but then changed my mind coz this gives me kinda 125 feeling when accelerating......