Just an opinion
Having an early 83 (#001), I have the heavy aluminum step plate molded into the cabin top - very sturdy structure, actually lifts the mast off the cabin top several inches. If you have that, I'd keep it, provided and assuming you can remove the 'new' step from the new mast and fit the new mast over the original properly. (Where did you get the mast?)You have heard the expression measure twice, cut once? Take your time, get a few people to look at it also before proceeding.As a final note, while you are in this major project, you might as well do the compression post, if it is original (see many archive posts on this, when the archives are back up!!). Also, check chainplates and other structure for weakness, so when you get done, you can be sure to have a most reliable rig.It is worth considering how the old mast came to fail, as that failure may have implications for the replacement and associated support structure.Feel free to email me off line - valveman@wi.rr.comGood luck,Geoff