I did some modification of head tube on my old bike to get another bikes fork to fit. Now I have shocks.
It was a job and it so far has held up.
The fork fit in the head tube as it was not the exact same size but slightly smaller. The races and cups fit so I suppose it did not matter for that issue.
The length of threads I had a the top of the head tube was not enough for the washer, lock nut, and crown nut. I fixed that by sawing a little off the bottom of the head tube.
If you did not buy the newer bike in the posted picture and need to get the measurements it can be difficult with the overseas companies that just don't have the time to talk to you I've found out.
If you get the information for specs that's a start as LB said.
MT
Page 16 post 151 picture show after cut the amount of threads increased to allow different fork with shocks. It is a 24 inch wheel on front and 26 on back but seems to work fine.
http://motorbicycling.com/showthread.php?t=29678&page=16
