I don't know what I'm doing: Modern drivetrain into a 40-year-old Honda

The transmission is fairly long, though.  Need to measure the whole drivetrain.  As installed by VW the bellhousing face is only a couple inches to the left of center.  The exhaust is also going to want to route kind of weird.  The biggest issue with the A1 chassis VWs is that the rack attaches low on the firewall.  A2 and newer have a subframe/K-member and the rack attaches down on that, the exhaust goes almost straight back over the steering.

A1 headers look... odd.  I have not seen what a 1.8t downpipe looks like but it can't be pretty.

Nope! 

From what the Honda firewall/etc looks like, you're going to have to fabricobble something similar.

There are a couple different layouts for the 1.8T exhaust manifolds. Depending on how hard you want to look you can find one that would just about come out in the center of the car. I know as I found one to do a 1.8T swap into a 83 GTI. Problem is I can't remember which car it came from.