Sounds like a fun project, one to keep an eye on for sure and some decent thoughts in your plans.
A few points that you might not be aware of since you're unfamiliar with these engines:
I have an AUG engine on the floor to build .
I don't think there was an AUG, though there was an AGU (Large port head, 20mm wrist pins) and AUM/AUQ (Small port head, 19mm pins). If you're replacing the internals then rods/pin diameter is largely irrelevant, but it's worth knowing which you have in order to build to a decent spec. Depending on goals, large/small port head may or may not be best suited. VVT is another one worth considering, as it'll
help spool on a larger framed turbo.
Edit; From later wording in your post you mention large port, so assuming you have an AGU.
The LP head will only really be beneficial above ~450bhp levels, depending on how you plan on delivering the power from your chosen setup. Below this rough threshold a small port head will
help to keep velocities high and increase torque.
No Leon came fitted with an AGU so hopefully you've managed to avoid the dated ME3.8 management, which is a bit crude (not necessarily a bad thing) and increasingly difficult to find a decent tuner who's willing to map it these days. Assuming the car you're fitting the engine to was running a 1.8t from the factory it'll be ME7/7.5 and should be DBW, which you can bolt straight up to your new engine rather than haivng to transplant the DBC throttle which will be a bit of a pain (though far from impossible)
AGU engines were narrowband so you'll ideally want to convert to wideband (either through ME7 management or standalone)
Unless you're goign for CSF/similar quality, don't bother. The cheaper alu rads offer no real advantage in terms of cooling, so the only benefit will be a little weight loss of both the rad and your wallet.
Cheap units tend to be bonded, not welded/brazed, which leads to poor heat exhange and longer term sees the core falling apart to some extent.
R8 coils with spacers and clamps.
Don't bother, they're not an upgrade as seems to get falsely thrown around the internet. People get hung up on them because they're red coils, and pay silly money for alu adapters when you can get dealer parts for under a tenner anyway. You don't need clamps to bolt them down.
Alloy lightened pulley set up.
Don't replace the stock crank pulley with an alu one. The standard part acts as a harmonic damper and without this you risk damage to the crank (have seen one snapped before as a result), as well as nasty vibrations.
Can't remember the name but got the blue cam belt.
Gates. These have mixed
reviews from the bigger tuners recently - they are more "brittle" than a standard part, and have been known to snap nastily. Stock quality belt should do the job perfectly and save you a few quid in the process.
Stock LCR injectors are 386cc, from memory. If you're looking to go above ~275bhp or so then go for something bigger. You'll often see 440/550/etc pop up at good prices for these engines.
Hopefully that doesn't come across as just slating some of your plans, but there are a few things on your spec list that either aren't necessary or should be considered thoroughly - taking some of that on board should result in you putting together a more suitable setup and saving a few quid too
What series are you going to be racing in?
all the best.
