reha you are more then well come, GS150 is a perfect choice for a tall person and has a very good Power to weigth ratio ....
My advice would be that please understand that is a pakistani bike and not tested untill its handed over to a customer and "may" have some basic faults like losen nuts and bolts bad paint quality cad Chrome or may be not preoperly assembled engine ...
So I would advice you to take somw sound friend who has a spent some time with a GS and he can check one or two units of GS150 in show room and indicate you wich one you must prefer ...
once bike is in your control and you remove any intial faults(bad assemblings) and which is kind of a fun .. then this bike is going to spend some Good time with you on long tours..
I dont own one but I checked it, 125cc bikes are no match its a Very Very Comfortable Cruiser.
@dr.omair can give some guidance on this ... he will be back on Pakwheels after few days..