Check out what model it is. The first Magna was the VF750S model which was sold as Magna on some markets. It came in 1982 and it was a mess. The cams wear down quickly the camchain tensior was not working the frame cracked down if you put on a luggage carrier etc. Next year came the VF750 F and the S models stopped and VF750C got the Magna brand. The bikes were still as bad. The Honda factory supplied cams and other stuff free of charge for years after the official guarantee had ended.
In 1986 came the Honda VFR750 which is the best 750 ever manufactured. Very strange that the VF750 F was a mess and then next model VFR750 had no problems. The biggest difference was that the VFR got rid of the cam chain and have the cams driven by gears, a very expensive system copied from the VF1000R racer. I know bikes with 200.000 and even 300.000 km in the meter and never any problems!!!!
Unfortunally Honda continued the VF750 C range with the old engine and slowly they succeded to fix the biggest problems. These bikes were sold as Magnas on some markets.
Aprox 1995 Honda came out with a new Honda VF750 Magna which is a very good and powerfull bike with no technical problems. You will leave all standard Harleys far behind you. The new Magna have some parts from the VFR 750 but it still has a cam chain.
Your bike is probably the old model and if so stay away from it.... especially if a Thai mechanic has been "maintaining" the bike. If for example the carburator package has been dismantled you will not find a mechanic in Thailand who can make them work properly again.
If it is the new model then it is a bargain. They cost about 150.000 Baht here in Pattaya.
Check up in internet what model it is. You can find all spare parts fiches for ex on
http://www.mrcycles.com/fiche_select.asp and then you can find out what model you have by comparing.
HIKO (former Honda dealer for 25 years)