modifications

how do all.  I am looking to get into cruising and considering a contessa 26.
I don't know much for sure about anything so thought I'd ask.
I know it would be work, so is getting out of bed in the morning,but too the point........
how hard would it be to  extend the cabin back to almost the cock pit seat lockers,keeping original structure intact and build lazzerette off cock pit combing forward to almost the cock pit seat lockers.  I would also raise cock pit soul quit a bit.  ????????
  Also probably not worth doing and a full blown mess but is it possible to replace the steel in the keel with lead.
I am a very handy craftsman, at least have been told so enough times to consider believing. concrete construction has been my trade.
   Thanks for any in put.    It's all new to me, even the sailing part