Personally i would only ever use Powerflex as replacements.
If you decide to fit original type then i strongly suggest you buy good quality ones.
I have done this job many times but i always remove the complete subframe and do it on a bench,repainting it all before refitting.
On one occasion i did it for a guy who supplied the parts and they were cheap copies of the original type.They fitted the axle frame o.k. but frame just would not go back into the car.Turned out they were both nearly 2mm wider than the max tolerance allowed.Out came the grinder.
You don't need to burn the old one's out,you can do it with a 6mm drill bit and a cordless drill.Just drill right through between inner and outer "rings" and the drill will steer itself all the way around until separated.Punch the centre tube out.
Then get a good hacksaw (the old type with a wide blade are best,more controllable).Take the blade off,put it through the hole and refit it to the hacksaw frame.
CAREFULLY saw through the thin outer wall of the remaining outer ring,remove hacksaw and punch remainder out.
Then clean the hole out thoroughly,preferably with a "flapper" wheel of suitable size on your cordless drill.You can also do it by hand with medium grade emery cloth or with a Dremel using sanding drums.
Good luck.