There have been a number of discussions previously on this subject on these forms. The only way to get a good job done on this is by a machine shop that can hold the conrod and ream / hone perfectly square to the conrod. It is real easy to do a poor job the way you would like to do it and then your motor wouldn't behave very nicely. An easy fix in this case should be seen as a false economy. Any yes, no doubt folks have done this "garage fix" and have gotten away with it.
You will have to make a pair of jigs that bolt onto the crankcase mouth, and are true to the crank . They will need to be able to slide together to sandwich the con rod and have a guide tube again true to the crank. As Peter has already said, a lot easier to take the crank out
Here is a thought along the lines of what Trevor suggested. I haven't tried it, but it might work. Use your old piston as a guide for the reamer with threaded rod and sockets to guide the reamer through the rod. You would need some way to either fasten the threaded rod or the sockets to the reamer. Set the piston on blocks or rods so that it is not moving (as if you were going to install the piston on the rod. Slide sockets or spacers which will just slide through the little end bushing as it is now onto the piece of threaded rod. You will want enough sockets so that rod and most of both sides of the piston are fully supported. Fasten the reamer to the end of the threaded rod and start cutting. Let me know if it works!
I don't know the size of the B44 small end but I used an adjustable hand reamer on my Ariel Square 4 small end bushings -- without any special alignment tools -- and that worked a treat. Be sure to practice a time or two on a practice bushing though. Unfortunately a good quality adjustable hand reamer can be costly to buy. If the size is a common one then a ball reamer (hone) should work too, so long as the existing diameter is already fairly close to what's needed. A 5/8" ball hone is about $20 USD for example. They take some practice too, but IMO a ball hone is a much safer bet than the cheap spring expanding brake hones which will almost always result in a bell mouth at one side or other of the bush.
One thing I learned watching a job in process, reaming bushings else where on the motor: DO NOT OIL them!! If the bush gets oiled prior to reaming, or even worse while attempting to ream, the metal will "absorb" enough oil to make the reamer cutting action almost non-effective! I made that mistake on valve guides,.... And now I know better!