@Tanveer: Welcome to PakkWheels
CG125 1990 is one of the deadly 125 ever came, in Khi this years 125's are highly favoured if in good condition.
Will suggest you to restore it to the full the total exp should not go above 20K in bringing her back to her original face.
Keep the 125 1990 with you its not just a bike its the moments you spent, as I have 3bikes hardly use them cause my uncle's dad and brothers use to ride them in their college days and when they come to my place and see these bikes is good shape I get a warm appritiation from them with lots of good talks.
And for your brother will suggest to get him a used MEHRAN a four wheel, but if he still wants a bike get him a new one. If going for new 125 get the DELUX shape 5 gears with front disk. I think 125 DELUX is more grippy than the regular 125 classic.
Deluxe costs PKR:115K its the most exp local bike avialble.