I had a M40XB (not M40A1XB) and from what I can remember, it had a one piece bolt handle, unlike most other airsoft bolt actions which have a two piece (handle and end cap).
The bolt handle also had no pins or ball bearings in it to stop it going past a certain angle (without a scope on the gun, I could lift the bolt up to 12 0'clock).
Your problem is that the bolt turns on the big fat part of the cylinder AND the spindle sticking out the end of the cylinder, where as most other rifles just use the spindle.
Even if you could reattach a new spindle, you'd still need to use an original SP bolt handle.
Hidakaya/BeMax made a replacement cylinder which came with the bolt spindle (unlike the gas bolts and other cylinders where you had to use the original parts)...
But as always, it's probably no longer in stock or has been discontinued.
I suppose you could get a VSR bolt handle and have a piece of metal tube welded on which would fit over the "fat part" of the cylinder and weld/bond a VSR spindle to the end of the cylinder.
I'll see if I can get hold of the fella I sold my SP M40XB to, he may sell it back to me or at least get some pics and measurements of the parts involved. The bolt handle should be the same.