Freelander 1 Overheating

Hi Freelanders. I recently had an overheating incident. I'm on the highway, gauge shot up to red. I stopped the car and turned the key off, pop the bonnet and had the old girl cool off. Upon inspection, I found a radiator hose torn, a little sludge on the oil cap (When I say little, I mean you have to scratch the cap to notice it. The deep stick is all usual oil), probably due to steam, water reservoir was all dirty (probably the steam burned the inside rubber and water started leaking through the cap). Pour in some water to the reservoir. No visible lick on the radiator, no oil leak on the engine block and when I cranked the engine, no unusual sound or rattling metal. What am I looking at? My obvious guess is as far as the top head casket. By the sound of the engine cranking, I don't think the piston seized. What's the worst that may have happened?

Knowing what engine would be helpful.

L Series 99 model 2.0 diesel

The L series is generally pretty robust, so you could find that simply repairing the cooling system will be all that's needed.