new to Micra K10

inherited a micra 1.2 auto MK1 .sadly very high blow by as cel's 3/4 scuffed after over heating. looking up cost of rebore .new pistons .rings .gaskets etc simply not worth investment or time. checking out for used engines isn't so easy as 1.2 K10 units are few and far between it seems. though have seen a lot of K12 units not exactly cheap but wont break bank. question I have a knowing naff all about these cars is the engine basically that same but just improved eg fuel injection? as if so would it be feasible to strip a K12 and use block and head with original list such as Carb. gearbox .starter etc.
decided car is not worth spending loads of cash on ( which as a pensioner I dont have anyway) so have stripped off cylinder head and started checking damage to bores . slight scuffing all bores mainly around top ends and assume possible carbon ? had got onto top ring section when head gasket blew . thus running with it may well have caused scuffing on bores . copying idea honing and new rings as rebore and new pistons is out of question. also looking at PCV valve renewing as though on removal it seemed Ok might well be a major factor in high blow by at idle and running .