Those do look like the same cap bolts on the 79' CB750 forks I have here, p/n 51454-422-003 and of course NLA from Honda. You might have some luck finding forks for the 79-82 CB750 on ebay. Heck, you might even find a whole bike for cheap if you look long enough!
The dime city caps could be correct, provided the forks are indeed the DOHC 79-82 variety. The Dime City caps are aluminum though, so be careful threading them in!