TR3 floor and sill questions

[JAMES_S_WALLACE@HP-Canada-om1.om.hp.com]

     I've just taken off the left side rocker panel on my post-60000 TR3a, 
     and the PO(s) had applied layer upon layer of replacement metal, 
     fibreglass, bondo, etc. It's hard to tell what's original because of 
     this, so could someone please advise:
     
     1. Does the outer lip of the floor panel end up flush with the top of 
     the inner sill?
     
     2. Is it possible to treat the inner sill with some kind of rust 
     converter and then MIG-weld the new rockers on, or will the heat from 
     welding render it ineffective? 
     
     Thanks in advance,
     Jim Wallace