Are there any bolt holes on the sides or front or back? Any 3/8" hole will work as long as you have the chain up tight against the block. And If I was pulling it out, I would pull motor and trans as a set, clean them as a set and then replace. It will be easy to change oils and clean the frame once the drive train is removed.
Loosening the head bolts is not a big deal. It hasn't run yet, so loosen a couple and install the chain. Remember to tighten them back down or you could bend them with the weight pulling sideways on them. Once you are all done and back together, just torque the two you had out back to spec's.
Once started and driven a while, you will need to torque all of them again.
Joe
