Changing U/C parts on a 943

I have to change the rails , segments and idlers on my 943 , just looking for pointers in doing this. I plan to cut the segment bolts with a torch. If the master bolts break it won't matter the current rails are shot. Not sure how the new idlers will come , hoping all those bolts will come out. Any advice would be appreciated.

Changing U/C parts on a 943