The same thing happened on our 147 JTDm 16v at about the same speed, some 6 weeks ago.
Talked to the local dealers, they said, its normally only the rocker arms that go and the valves are OK.... some times the hydraulic lifters go to and become noisy, not that often and worth the risk if I was doing it my self.
Did it my self, not too difficult. Read the manual before you start.
Took about 2 hrs to take it apart and 3.5-4 to put it all back together; not having done it before on this car. Easy to see which rockers were damaged.
Borrowed the Haynes Saab 93 2002-2007 (same engine) from the library for torque settings
Parts: timing belt kit, water pump, aux belt + pulley + tensioner (£200.00 all in from factors) and 8 x new rockers (£7.50 each from alfa) crack detection spray on the "good old ones" showed they were OK. I know I should of replaced them all, but the spray said they be good!
Timing tool set (£80) and crowfoot adaptor set (£15) to do up the injector hose nuts.
Got it compression tested at the same time as the MOT. Now 3000 mile on.... all OK
Most importantly I wanted to do it, I'd already done the cam belt on my 156 2.0 TS, so was confident in what I was doing, had the tools and the time.
Only do it yourself if the same conditions apply, otherwise let the pros do it, it'll cost less in long run should you muck it up.
Best of luck