I'm not sure you fully understand how these work......
The gearbox that is present in the pics is not a CC gearbox. Judging by the size of the pulleys in the pic, the ratio is far different than the correct box. If you plan to use it and not the proper box, you are going to have to build all your own mounting system. None of the info we can give you about the correct one will help. You'll be on your own on this one.
I'm not sure what you think a tiller costs.... but they aren't "unobtainable". Typical sale price is between $300 and $400. Gearboxes usually go for around $150 or so with the lower mount for the tractor. If you want this to work, your really going to have to find the right one. Or ask your dad to help. Looks like he's done some fabricating before....
Like I said... you really kind of have a mess there.
