Besides the Nikasil issue, which should be resolved or irrelevant by this point (although in some cases it can still raise its head) I've found E34 V8's to be pretty damn reliable, unless they've fallen into uncaring hand and have been thrashed, unserviced and generally abused - in which case you get the 'usual' issues that stem from cases like that such as headgaskets.
Don't buy one that's making funny noises.....makes it easy.
They can suffer oil leaks from the rocker covers too.
The V8 is harder to work on than it's six-cylinder brothers, too. There's a lot in that bay
Mine was chipped and considerably epic, it was hillariously quick and beautiful to drive - despite having done 180,000 miles. Had a few suspension knocks and the AC had packed up but you could forgive it that, as it wasn't the finest example by any stretch

I loved it though.
They are evil sons-of-a-guns.
I was averaging something stupid like 28mpg in mine, commuting, too. Couldn't complain.
Had:
- Automatic stability control
- Sports steering wheel with airbag
- Leather seats
- Shadow line trim
- Electric tilt and slide sunroof
- Auto dimming interior mirror
- Myrtle wood trim
- Rear headrests
- Headlamp wash + intensive wash for windscreen
- Air conditioning
- Park ventilation
- Multi function steering wheel + cruise control
- Hi-Fi speaker system – BMW
- M-Sports suspension (now superseded by the AC Schnitzer sports suspension)
- Warning triangle & first-aid kit
As well as the usual stuff like ABS, PAS, remote central locking, electric one-touch windows, electric mirrors, cruise control, front and rear fogs, trip computer with numerous functions, dash display with bulb-out warnings, you name it.......
Even had auxiliary heating - petrol-fired heaters that ran on a timer to pre-warm the car when you needed to use it, i.e. before you left for work in the morning.