I had a look at the advert. Seems to be a nicely built boat and a good price. Hard to know if the photos of its condition are current though. My experience is that they are frequently not, and boat interiors suffer in the heat and humidity of Asia, especially if closed up for any time. It looks like the motor will be used often in coastal sailing, but downwind around the world it should be a steady performer and comfortable.
It should be easy to design a balanced junk rig for this boat, assuming the original rig was balanced. The sails will overlap the masts, so the luffs will be further forward, but there is more sail area at the leach (because of the yard) on a junk sail to compensate. The masts rake aft, which is not recommended usually. Vertical or slightly forward raked masts are preferred because theoretically it helps the sails to stay winged out in light winds. But I find this is mostly an advantage only in smooth seas. In a developed swell, yards and battens swing around anyway. All sailors curse in those conditions, no matter what rig they sail under.
So, if the boat is is good condition then it looks like a nice cruiser, provided you like heavy displacement boats. If it were possible to have a test sail under the old sails it would tell you a lot. It seems unusual that it has no sails at all. I assume it sailed from Europe.
Whatever you do, do not buy it without a close inspection. Despite a lifetime of experience (but alas, also a lifetime of rash decisions) I did just that recently, because the boat belonged to someone I knew, and had done some extensive coastal sailing. Now I am having to do a lot of work on it and it will never be a great boat.
Good luck!