My car has not had an fuel problems. I installed a cell and it has been good so far. Some cell installs in other cars have not worked right. Some stock tanks have had issues too. Like Jeff said, most early cars were abused and neglected.
With carbs our car doesn't need a lot of electronics to run, just a questionable distributor. EFI cars are probably like an E30.
Brakes should not be a problem but you have to properly set them up. My car has had no brake problems. Rear drums on early cars are less than impressive and may need adjustment to maintain good pedal through a race. If you put on rear discs, that problem is gone.
Old rubber stuff in almost any brake system will die if you run a long time in a race.
Clutches/transmission is pretty much all driver error. The more drivers you have the worse your odds get.
Added compression stresses the head gaskets more. Long aluminum heads do not like to get hot. Add heat and compression and you are playing with fire.
The 80's Zs are glorified Touring Sedans, especially the first gen 300ZX. They are like the Cadillacs of the Z car line. Some 280ZXs head light washers for crying out loud. However, they are newer and seem to be more reliable.
Zs are fun cars but they have their issues. Once they are in the $500 range they start having MORE issues.
In a Non-LeMons form, the 240Zs still set records. I think they set a new record in Florida this year. There are solutions to many of our problems but they can get very pricey and exceed the Lemons budget.
Troy
#35 LRE
1973 Datsun 240Z