At first glance I would say they are Marzocchi, especially when I look at the casting detail by the axle. But, I am not familiar with the area of the fork by the seals. I have never seen a set of Marzocchi bulge like that. Look at the pics people have posted, they dont look like that in the seal area. Also by the bottom of rubber cover it looks like it has been fitted into a machined recess (?) and I havent seen a set of Marzocchis from that era done like this (later on yes, but in the 70s no).
The up shot of that is that on first glance, yes, Marzocchi, but when I look closely I am included to say no (definately not) and that they are probably of japanise origin ~ and I know very little about Jap bikes so wouldnt have a clue about what they could be off!
Not sure about the yokes as I can see any of the detail in the picture. Definately not Marzocchi, but could look a little bit like Simons? Would like to see a close pic.....
Nice bike though!