best thing you can do to your road master is to put a 250cc Night Hawk/rebel engine in it.
It would be a bolt on fit with abslutly no alterations
Bike will be automatically upgraded to 5 gears and CDI ignition
You wil get 4 more Good Horses (4 HP gain) and 5 more Torque units..
now a day even a Chinese Clone CB250 engine is fair enough and has even one more extra HP then the orignal Honda due to daul carb.
Availability of such engine is going to be a search of a needle in a hay stack..
There is no engine at ranchore line right ow of this series
There was one Night hawk enigne in Lahore Bilal ganj which was sold for 71k with hard negotiation (so you can imagine)
A chinese colone used to be available easily around 12~18k but even those are above 40k.
Thanks to owners of Road Masters 
please PM me your number and I will update you on weekend if I found some lead on it in a "insanoon wali price"
hope that helps..