I ran into the same problem this summer, I ended up just setting my engine on the ground after trying to find suitable thread material all over the place [I have one engine on the stand, but the stand was actually cut to let the bolts work]. Eventually I'll probably have a set of bolts made assuming I keep working with Hondas.

And yeah, flywheel bolts are 17mm, clutch is 10mm, both 12 pt.