Troy, I'll take a shot at it. First, how hard do you drive it? I'm assuming you have not added any remote cooling gadgetry, and you probably don't stick to the 65mph max people with Beetles are used to?
The only time I've ever had a similar experience was in a Beetle. I drove the car from Arlington, Va., to Odenton, Md. That's a thirty-something mile drive, all flat ground and only one traffic choke point. There were three stoplights, all at the beginning of the drive.
I didn't vary the throttle a whole lot for the parkway segment of the drive; 'long about 20 miles. I was cruising along at about 70-ish. I didn't really want to take it much faster because, well, it was a Beetle.
The engine temperature was well into the 200-degree range. The car was a quart low on oil, and an unmolested example of a 1641 engine with a single carb manifold.
The engine overheated -- it still ran -- but it ran hot. I shut it off to get fuel, and it didn't start again for about 25 minutes.
When she did start, I gave it an oil and filter change, an oil additive (SeaFoam), cleaned the case with a chemical degreaser -- and didn't do anything else.
I changed up the driving habits a little bit for the remainder of the week I had the car, and she behaved a lot better. The difference was nothing more complicated than dropping it to the 65mph max, and occasionally dropping about five miles per to vary the fan speed -- on the advice of a friend.
You might run a little foamy engine cleaner through the fan while she's running, then chase it with some water from the old garden hose. If the case is all sludged up on the outside, it's probably not dissapating heat very well, and a degreaser will certainly help that.
Lane's vapor-lock is a possibility also. Re-routing the fuel line as far away from the block as practical is certainly a good idea. While you're at it, I'd make sure you don't have the little clear plastic fuel filter in there. Get rid of that thing, if there is one!
You might have a look under it, too, to see that all of the cooling sheet metal is still there. It's one thing to blow air over the cylinders from above, but you need the air to make it all the way through, in order to carry the heat completely away from the bottom of the block.
I'd have a look at the engine compartment itself, too. Make sure the tins that surround the engine really do 'surround' the engine. Keep the cool air up top, and keep the hot air from rising back through gaps.
If your carburettors are set way lean, you might be hotter than you need to be. If they are rich, and it sounds like they might be, just a touch, you could be cooking off unburned fuel in the exhaust pipes. If they're adjusted properly, you might need to adjust the advance a little. I'm not the smartest guy in the room on carbs; I'm just ballparking.
Back to the driving habits part; we sometimes forget that the car looks a little racier than it is. I'd be willing to bet that a lot of these cars' heat problems stem from us owners driving them like race cars. ;)
