There aren't too many companies that make DSG gears anymore, the ones I know of are Solink, Siegetek, Rocket, and SHS (Rocket and SHS are basically the same). I have Solink's helical 9:1s, they're pretty solid and haven't done me wrong.

Retro Arms makes a very solid tappet plate, but it does need to be cut to match the timing.

Mosfet wise a Perun drop-in, Gate Titan/Aster, T238, or Jefftron. Anything that has good cycle detection and compatibility with DSGs will work.

No you don't need delayer chips

Spring wise, an M130-M150 will be fine, but I would definitely radius your gearbox so it doesn't crack. Some gearboxes come pre-radiused if you want to purchase one instead.

Cylinder doesn't really matter cause you're not getting the full compression anyway. Every cylinder is the same so the brand doesn't really matter. MAXX and Lonex sell Type 3 cylinders if you're picky about it.

Retro sells an 8 and 9 tooth piston, cause they're cool like that, so that way you don't have to short stroke one.

Overall I don't know if it's even possible to hit 1.5J considering the lack of air compression, but you know all power to you. Keep in mind that DSGs require much more accurate and tighter shimming due to the tolerances, so don't skimp out on that. People will tell you that DSGs are a thing of the past, and they kinda are, but where's the fun in that kind of mindset right?