Just my opinion - but - if the vehicle is going to be daily driven & see any significant highway usage, you're going to be quite unhappy.
First - the gearing is going to be way off - you're taking a vehicle with a powertrain designed for a high revving, medium horsepower gasoline engine, and mating it to a diesel which produces way more torque, but in all likelihood (I don't have the numbers for the VW engines) less horse power, and peaks at way lower rpms, and you're going to have very limited gearing choices to correct this.
It's been my experience (which has been on factory diesels, which would supposedly have been close to ideally geared, rather than swaps) that small automotive diesels are woefully underpowered, to match the horsepower of the 2.0 J20a engine, you're going to need a turbo diesel upwards of 2.5 litres - without horsepower, it won't accelerate the way you're accustomed to - you're going to find overtaking on a two lane (one in each direction) an absolute nightmare, and also merging on an onramp.
To touch briefly on your timing chain/guide issues - three different engines, three different oil pumps, and what sounds like three timing sets from the same source - doesn't that tell you something?
Direct question - what sort of gasket was supplied for the upper tensioner adjuster - metal or fibre? Have you ever seen the original gasket - it is a one use only metal gasket and it has a metering hole to control oil flow out of the tensioner.
Second question - where did the top guide break - right where it was folded?
I just want to give you a couple of things to think about.