Maybe but every time you buy a used 80 you are probably buying more pattern parts than genuine. I'm not saying don't buy non genuine but avoiding having then is probably wishful thinking. Unless you strip everything off your truck and start again. Starters, alternators, bearings, pads, exhausts, UJ's bushes ....
The problem with genuine is cost I guess and the difference in quality over price for some parts. The question here is, are these parts dangerous and if they aren't are they value for money over genuine. The problem with brakes is that even genuine ones have a tough life and don't last that well. Should you fit a new set every year for 4 years or fit a genuine set and expect them to last 4 years. Not an obvious call.
Personally I think I'd prefer to take a set of known to be genuine and have them rebuilt by, say, Bigg Red.