Josu,
I can see that your second machine could get the rough grinding accomplished at a low cost. However, I prefer another option, which can be just as effective and done at even lower cost.
I have used Norton 3X forty six and eighty grit grinding wheels. Either one will work; you don't need both. They cost about $50 US each. They grind quickly. They are not an ideal match for the Tormek out of the box, however, they can be easily modified to work well.
Norton only sells 3X wheels in 6and 8 inch diameters. The 6inch size is too small for any Tormek. The 8 inch diameter fits the T4 exactly. It will work with the T8 like a regular wheel worn down to 200mm or 8 inches.The one inch width is narrower than the Tormek wheels, but is surprisingly useful.
I have described several methods of mounting the wheels. My latest preference is using a steel reducing bushing (1” to 12mm) from D-Way tools. These adaptors for either size Tormek very well. You must use several nylon spacer rings (1” ID, 1 1/4” OD from a hardware store) to fill up the width difference. This is less complicated than it sounds. As the reducing bushing is not stainless steel, ACC or other antioxidant solution is necessary. Including all costs, this is still an effective, low cost option.
Choose whichever option you like; they all work.
Ken