Doesn't really matter what type the calliper's are as their already fitted.

Basically, lug mount has, as description, lugs on the inside that allow the calliper to be bolted directly to the knuckle. As such there no adjustment on disc diameter, and only a little (using spacers) on offset.

Lug Mount

Radially mounted has a machine billet or casting bolted to the knuckle. Socket screws are then used through the calliper from the direction of the wheel rim to the driveshaft, to bolt it to the bracket. By the size and where the holes are drilled there is a wide adjustment of offset and diameter, limited by the inside radius of the calliper adjacent to the disc outer edge.

Radial Mount

The disc offsets I've given you above (from the Tarox catalogue) are the distance from the outer side of the disc centre (which the wheel bolts against) to the inner disc face. So if you measure from the centre face to the outside of the disc and add the disk thickness...that's the offset as listed above.

I would think whoever put the system together, from the disc diameter and construction, has just used Cosworth discs. If that's right, than as I said before, once you've identified whether they're 2WD or 4WD, you can choose from many aftermarket suppliers.

I would think the discs are likely to be 2WD, as that used 4 piston Ford callipers like the Wilwoods I think you've got. The 4WD used a 'sliding' calliper, so didn't need so much clearance on the inside of the wheel.

Don't forget to change pads as well! Rally Design (and others) can supply a range of materials to suit usage of the car and your driving style.

Cheers

Martin