It has been many years since I’ve dealt with those bolts, but I do not recall them being left-handed thread. There is no logical reason why they would be designed in that matter.
As a side-note on this topic, I took the advice of other owners, and did not reinstall those two bolts. This will allow future removal of just the ZF instead of also having to remove starter, clutch linkage, etc. I did this probably 15 years ago and there have been zero issues.
Larry