Nothing wrong with replacing your bushings, no need to replace the whole arm as the Arm itself is NOT a wear item, bet was though is the replace the shaf as 99% of the time the inner sleeve for the pivot bushing is rusted to the shaft anyway, so order up some new bushings and a new set of shafts and cut your current shaft in half and then use a air chisel to drive out the bushings , start by getting under the outside lip,and work it out. , for the install you can use a ball joint press to press in one new bushing , but you are gonna need a stand up press to press the other one on, just remember to install the new shaft with all washers before you press in the other bushing..lol and have something cut to where it firs between the opening between the opening on the inside of the arm, otherwise it will try and fold up the arm when you press the other bushing in, I just cut a section of exhaust pipe and that works fine. just did a set for my buddies caprice yesterday in a hour.
1) "Nothing wrong with replacing your bushings, no need to replace the whole arm as the Arm itself is NOT a wear item"
Not sure what kind of truck/car you are referring to but me thinks you may not have done many front end rebuilds on 73-87 type GM trucks: the A-Arm bushing area in fact DOES
get worn because owners neglect greasing and once the bushings have worn completely thru, the A-arm itself takes the brunt of the wear to the point that it's turned into junk: unusable, no matter how many new a bushings you install.
2) "cut your current shaft in half and then use a air chisel to drive out the bushings"
Unless you've got a cutting torch, I'd say that's a lot of metal to cut thru.... inch and half maybe 2 inches? And if you need an air-chisel to drive out the bushings I would pretty much think that at this point the a-arm itself is trashed or WILL BE trashed when you bugger-up the bushing's mating/surface area with an air-chisel... my .02 cents.
3) "use a ball joint press to press in one new bushing"
Never used a press to either remove or install the bushings on the a-arm because they thread onto the a-arm shaft. Only the ball joints needed pressing. But then again, my original a-arms were USED (very used) and it was only later that I found the front end alignment would never take because this is where you get all the play, i. e. new bushings in OLD WORN a-arms is a waste of one's time, energy and money.
From my own personal experience, if you take the truck to a repair shop worth his salt, he won't even bother talking about replacing JUST bushings on the A-arm, he'll tell you to replace the whole A-arm Assembly--- NEW--- OR he darn sure won't warrantee the work.