Guys,
remember the most important thing about a ROPS.......if you choose NOT TO wear your seatbelt while using the tractor, it doesn't really matter - the ROPS really does little to save you, much like an airbag helping those who choose to not to wear a seatbelt. Both need each other to work properly.
If mine - I would cut the ROPS and leave whole, allowing enough room to get under the header of the garage.......If I could not weld - I would have someone that is "good" at it do it.
If cutting and placing the sleeve in the middle - I would make sure the fit is perfect and bevel the meeting ends, allowing the weld to meet all three points. I professional welder will do this anyway. And a welder will make it as strong, if not stronger than before, I say all of this knowing full well the height of the ROPS is one of the key factors of roll over strength.
If we look at all the safety equipment that is now on tractors....they are there for a reason, safety switches, pto covers etc.......BUT they are really there to protect those who are not smart enough to protect themselves.
I bet that 90% of us (some will not admit) DO NOT use the seat belt - and yes, I am guilty as hell of it! OF my 200 hours, I might have worn it 10 hours.....I know - bad me! I do wear my belt q100% while driving car/truck....I have no excuse while on the tractor not to......