I think its crazy that guys will spend 10k on their tdi in pursuit of a measly 300 whp! Save yourself some grief and enjoy the car for what it was intended for...efficiency and practicality. First of all these cars are plenty of fun as is with a simple re-tune and second to that, I have found that many simply are not resourceful which is why they spend so much ( i know there are exceptions and this is not intended as an insult). Be realistic about your goals and be smart about your upgrades and you can come up with a very fun combination that will not cost 10k. Since you have a pd you will quickly realize that it is stupid expensive to have the nozzles upgraded so why not maximize the potential of the stock nozzles. The passat was blessed with the pd130 injectors which are very similar to the pd150 units and they can support upwards of 230 bhp or about 200 whp. If you stick with the stock injectors you will save yourself a grand or more right off the block. The bhw was also blessed with a pretty stout bottom end so you dont have to worry about different pistons or rods. The cylinder head flows well in stock form and the stock bhw cam is the best stock grind available for the pd...if it is in good shape! Basically what I am saying is, you already have a solid platform so appreciate it for what it is and stay within its boundaries. A malone stg.2 tune and a good gtb style turbo (gtb1756 or 2056) would suite that car nicely. I wouldn't do much more. A franko6 reground cam would be nice but thats a pricey upgrade although its more for longevity than performance...all good in my book.
Now for the transmission...the 1.8t ezg transmission is the worst possible choice. At the very least find yourself a DVZ out of a v6 passat. You could take it a step further and purchase the tdi 5th gear set from advanced auto motion (500 bux) and have that installed for a decent compromise. At that point though you are almost spending as much as it would cost to just buy a real tdi gearbox from Europe. If you are resourceful you could do what I did and buy a complete tdi gear set (input shaft and pinion) with ring gear from Europe and have that installed in your ezg case. I was able to save loads on shipment and I have an uncle who builds transmissions so labor was free...total cost was 400 including donor v6 tranny.
Finally, you need to look into the balance shaft module issues you are facing plus the cam issue. Get those sorted before you do anything else!
Good luck and have fun.
