Yh the other night i dropped a valve on my gk76a and mashed the top end so im wondering could i fit the gk73a engine or atleast just the top end and no the bottom end?

Simple answer is no.
Different mounting on the heads.
You cannot even swop valves over as they are a different diameter shaft.

Dam that sucks well i ordered a gk76a full top end gonna do the timing, valve clearences and new gaskets aswell of course but what i just wanna double check is..

is the timing on the gk76a 20 pins or 19 i do believe its 20 correct?