Should last forever!! Could be the cheapest £350 worth of motoring you ever bought...

Just watch out for noisy cam chains (replace it) and sticking idle control valves (clean it out).

We had a customer with a DOHC engined Granny which was still going strong at 190k with no smoke. Just had a head gasket at 192k and off it went again for another few ks before he sold it on...