I know it's a little late but here's my opinion.... I have a '79 Spider and I am a big fan of that particular year. '79 was the first year for the 2000 engine and the 1st of 2 years that it was carbureted. The benefit of that engine was that it was the biggest engine that was in the 124 Spider line. The drawback was the weak carburetor was choked out by pollution control add-ons. The fuel injected version did a lot to rectify that, but I like the carbureted version because of the flexibility that it gives you for performance upgrades etc. I have replaced my original carburetor with an after market carb that has given me a nice increase in performance without the complexity of fuel injection.
As far as the body style, the significant change between an 1800 and the 2000 are the larger hood "humps" (one over each cam), flush mount door handles, and the angular tail lights. My personal opinion is that each of those make it more aesthetically appealing than the 1800. The bumpers are an ongoing source of discussion for Fiat fans because the large tubular bumpers added on a lot of weight at the extreme ends of the car and had a negative affect on handling although the car has good handling none the less.
As far as the interior, I can't think of anything off-hand that is remarkable about the 2000 vs. the 1800 so there is not anything there that I think would influence you for one year to another.
So here's my rundown:
Pluses for the '79 2000 Spider
- Slightly redesigned exterior distinguishes itself from previous years without a complete departure from the bloodline.
- Largest engine made for the 124.
- As all Fiat Spiders go, nice handling and good sporty appearance (although removing the bumpers will improve handling)
- The most recent model year ('79 - '85 were pretty much the same car except for the fuel injection) so parts are easiest to come by.
Minuses for the '79 2000 Spider
- Stock carburetor should be replaced to get good performance
- The tubular bumpers are too heavy for the purpose they serve
I'm sure other people will have other opinions on this, but that is what come to mind immediately.
As far as what to look for:
* Check the tail lights make sure they work. They are on a circuit card and it can be hard to find another if that card is damaged.
* Check the oil pan. The oil pan hangs pretty low an the 124 Spider and is in constant risk of being hit hard. It may be a little banged up but if it banged hard enough it will break the oil pick-up off and if that happens and is not fixed soon enough the engine could be damaged.
* Check 3rd gear. For some reason the shifting arm for third gear gets bent (probably from the driver resting their hand on it). Mine stopped shifting into 3rd gear and when I had it fixed I was told that it wasn't uncommon in Fiats.
* Check the brake compensator in the rear. The brake compensator is in the back above the rear axle on the (European) drivers side. I have had to replace this because the seals dried out. This may not be common, but I have notice that some parts dealers sell a compensator bypass hose so there may be a reason.
* Electrical things in general are always good to check.