Gear boxes / transmission suggestions

The first option will work well for your setup. The second (.83 4th gear) would probably not, as the gap between 3rd and 4th gear is too wide and the smaller engine would  struggle trying to pull in 4th gear.

VW also made a .89 4th gear which lowers the revs in 4th nominally (and opens the gap a little and that could work for you but I think the .93 is probably best for what you're intending for the car.

With normal wheels and tires, at 60 mph in 4th gear you'll be turning about 3000 rpm. 70 mph will be about 3500.

It's a little noisy and the revs feel a bit high to people used to modern cars but that's just about where these engines want to be.

The first one looks like  std AT transaxel? (In looking at trans code charts it looks like all Karmann Ghias came with 3.875 R&P --- https://www.limebug.com/how-to-guides/view/32   

The first trans you've linked is a late Beetle trans- VW went from .89 to the shorter .93 in 4th when the 3.88 ring & pinion was introduced (late 1972?) because the Beetle couldn't carry the taller gear, whereas the Karmann Ghia's better aerodynamics allowed it to keep the .89. Look at the side by side comparison of the 2 stock gearboxes below- 

 http://www.teammfactory.com/ca.../0/0/3600/3600/1/0/2

A Speedster is a lot like the Karmann Ghia in that it can carry the longer .89 in 4th, even with a 1600. This will be a fun, no hassles combo. Stay away from the "freeway flier"- as Ed has said, the .82 4th won't work, as even a 1776 is too small for the wider than stock spacing. Look below at the rpm drop when you shift from 3rd to 4th at 3500 rpm with the taller gear- a smaller engine doesn't have the torque to carry the car in this gear at this speed, and overheating the engine can result if you're not really, really careful. Guys here (and on the Samba) have reported that, even with  a 2 liter or bigger, the longer spacing with the .82 in 4th is just awkward. 

http://www.teammfactory.com/ca.../0/0/3600/3600/1/0/2

If you think the 1776 will stay in the car for a while, you'd like the car to be as zippy as possible when you're out and about and a high cruising speed isn't a big priority, consider going with a 4.125 r&p- it will make the car a little more fun at lower speeds. Input it into 1 of the gearsets with the .89 4th and see what it does. 

Hope this helps. Al 

@WOLFGANG said- "In looking at trans code charts it looks like all Karmann Ghias came with 3.875 R&P" 

The KG used the earlier ring & pinions (4.375 and 4.125)and switched to the longer gears at the same times as the Beetles did, as power and displacement went up, Greg. The gearsets in the earlier boxes are the same as the Beetle units until the switch to the 3.88, when the Beetle got the 0.93 4th and the Ghia kept the .89.

Thank you very much guys, that's really helpful. I feel a bit more prepared to make a decision now.