Hi John,
I can't see any real problem with having the 2in barrel machined off other than getting metal chips on the optics causing scratching and also the cutting fluid for aluminium is fairly oily (I use kero due to the stickiness of aluminium). I don't know your particular eyepiece but it may be possible to remove the optics prior to machining - I know my current Televue eyepieces screw apart. I reckon have a go
Chris