Warning this will likely be long winded.
My car is over built in many aspects and there are very few bits that are Datsun 1200. My local group VARA has a catch all class that I run. I'm in with the B-sedan car (mostly 2002s and 510s) which is where the car would run if it were 100% legal. There are minor things the organizers would be OK with but the one thing they are not is the keihin flat slide motorcycle carbs........I'm not changing those so I run GTL (under 2 liter GT)
Most of my maintenance is oil changes after 3 events and adjust the valves after 10-12 events. I only do 4-6 events a year. I milk a set of tires 2 race weekends and 4 track days. I run the fresh tires from 2 races and then they become track day tires.
The key for me has been under tuning or over building it.
My last engine went 5 seasons and only broke because the motor got hot and I failed to notice it right away A full on race A15 (1500cc) makes 150whp. My 5 season wonder made 99whp, I'm currently doing up another motor that may be as much as 125 but more likely around 110. I won't run something that won't go at least 3 seasons. I went to the 1500 from the 1200 motor because you had to buzz the A12 motor up to 8600 rpm and that required reringing the motor every year. I only rev the A15 to 8000rpm. If you run a motor 80% of an all out race engine it will go forever.
I was running a close ratio gearbox but those are fragile, so I've gone to a larger 5 speed. Initially I whined about the ratios of the street box but as it turns out the ratios are such that I only use 3rd and 4th plus I make fewer shifts.
The rear axle is an H190 (190mm ring gear) where as most run a H150 or H165.
The brakes on my car are 280ZX and the rears are 240Z. In the 26 years since I've installed the ZX brakes I've never worn out a set of pads. I just change them because I figure they get harder with age (no idea if that is actually true). The rear shoes take about 5 seasons to wear out. My car with me in it is 1786lbs (I'm 140lbs) so having brakes from a 3000lb car is definitely overkill.
The front suspension is 280ZX as well so the massive wheel bearings relative to the stock ones mean I only have to change out bearings something like every 10 years (I've raced the car for nearly 30). I use Koni dampers and they are long lived.
If I get put in the small bore group I usually finish 5th out of 25-30 cars. Lately they have been sticking me in with the B-Sedans, in that group I'm running 8th to 10th out of 15-20 cars. I'm a better than average driver so I'm able to finish a couple of spots higher than an average driver would.
In B-sedan the leaders are 9 seconds faster than me on a 3.4 mile course. There are 3 or 4 cars that are 3 to 5 seconds faster than me. I'm going to spend around $750-$1000 that will put me up with them. After those cars the next closet cars are 7 seconds a lap faster, catching up to them means spending $3000 more as well as having to refresh the motor every 10 events, which is a bridge to far for me.
I know I'm driving well, I'm having some great dices with people and so spending $5000 or $10,000 more because it makes me ego feel better isn't worth it for me. This is supposed to be fun and I find it fun battling my way past faster cars.
So short story long if you overbuild the drivetrain and brakes and keep the revs down the car shouldn't be fussy at all. Also a good driver can drag a car a couple of places forward at vintage races.