Electronic ignition, hence engine rebuild - 80 series

Ok, here´s the deal, I´ve got an 80series with a worn out 3F engine, knowing that I´m sydney based, what would be the right thing to do?, 1-rebuild, 2-exchange, 3-get a different kind of engine, knowing that I´m sydney based.

PS. I have just installed an american electronic ignition in it, all electrical bits and pieces have been replaced (spark plugs, leads, etc), aparently this has killed the engine that already had 280000kms on it. It looks like cilinder 2 and 4 aren´t working anymore.
Ulises