Thats funny, I have seen this post somewhere else
I answered your Q on redline but to summarize
It's the torque that breaks these gearboxes, remember they were designed the gearbox to mate with 55hp 3 cylinder and 70hp 4cyl engines.
They made the diff a little bigger for the 100hp twincam but everything else is pretty much the same, we call this family of gearboxes "small frame" as they have a 60mm centre line between the two shafts.
The other range of gearboxes is the Large frame which have a 70mm centre line, this means thicker shafts, bigger bearings, bigger teeth on the gears, these boxes all have a cable shifter and came on swift sedan, Aerios, sx4's etc, the general opinion is about 180hp max on the small frame box and roughly double that for the large frame box.
DMW on redlinegti is the guru of doing the conversion and can sell you a few small pieces to make the job easier and well as a billet flywheel, the stock flywheel for the large frame box is insanely heavy.
Suprf1y/3 tech/Mike on this forum can help you with cams.
I can't iterate enough the value of reading up before you ask questions, you'll get more help when it shows you're tried to research it first, granted some of the forums aren't always easy to find the answer but I guarantee what ever you're asking has been done before.
Keep those photo's coming, especially the dry sump setup