Hi, when i looked at the specs of the european choke type 35w Sox ballast, i saw that the current is same as the 50w mercury vapor ballast (0.60 amp). As finding ballast for 50w mv lamp is near impossible in here I wonder if sox ballast can run it properly?

Well, a parallel connection of ubiquitous 36/40W fluorescent choke and 7/9/11W PL fluorescent choke will give about right impedance (within about 1.5% overdrive) for 50W mercury lamp. Much easier to obtain than messing with SOX ballasts.

To run a SOX 55W one could maybe also use a choke ballast for 36/40W 1m tubes. Their lamp current might be close to the SOX (560-580mA). Of course an ignitor is also desired.