Cbm72 head leak

[CBM72]

Hi my name is Eddie, I have tried to post on here in the past but never could because of my computer and I would always forget my pass word, then just wouldn't post , any ways I have a 1963 cbm72 hawk, my dad brought it back from japan when he was in the navy, I restored the bike which was in very bad shape about 16 or 17 years ago. I used to ride the bike a lot then it sat for a while, long story short I rebuilt the motor once and it was fine then about 7 years later she started developing a head leak, oil would weep from the front of the motor , not bad but I couldn't stand it so I tore it apart and rebuilt it again, it developed the same leak, then took it apart again and replaced all the roller bearings, seals everything , I thought the leak was because I had a bad head gasket the 1st time, 2nd time I thought the green o rings were not getting squished or were bad, 3rd time I used copper coat on the head gasket and it did not leak for a few days then started again, I let the bike sit for a year and now I have motor out of the bike and the top end off, going to check it for warpage , and might have it milled, and before I put it together do you guys have any advice? The breather and gasket on the top is located with the holes to the front, just if you are wondering. I was also worried about stud stretch? Maybe the studs might be the problem?? Also the last time I replaced the head gasket I used two copper washers on the top just to make sure the acorn nuts weren't bottomed out and it still had a slight leak, it doesn't leak like a old triumph, but it's a honda it shouldn't leak and when I rebuilt it the 1st time it didn't leak for years and I rode it a lot, any advice is appreciated, also I can't find good head gaskets, the 250cc is a lot harder to find gaskets for than the 305, I just ordered a pricey vesrah gasket set, hope this is better than 40 or 50 year old gaskets that I keep finding, I will post pics if I can figure it out,,,I'm technology ignorant