The early 750,s leaked but slowly honda updated the design with extra rubber bits in the head , so if yours is the k6 then it should be the least likely to leak, however if you are using a head gasket from an aftermarket set then it might pay to give it an extremely light coating on both sides with blue hylomar, i have done this on several bikes including a 77 cb750 with great success, i must stress it has to be a very thin coat, preferably with the spray version, this is just my opinion maybee someone else will chime in
pete