I don't think it really matters which direction the nuts are facing. The important thing is to remember to install them. No kidding, as you can see from the pictures, I made a rather alarming discovery when removing the engine on my 66 Barracuda. Sometime back in the car's past, a so called "mechanic" did just that.. didn't reinstall the mount bolts and nuts.
This happened so long ago that the steel part of the mount had rubbed a 1/8" depression in the block. The engine was sitting almost an inch low on one side. The passenger side exhaust manifold and fuel pump hides the bolts unless you are specifically looking for them.
It appears the engine was raised off the mounts to remove the steering box. I suspect this because the "mechanic" broke or lost one of the steering box attach bolts and replaced it with another bolt that was an inch too long... complete with 10 flat washers to make up for the extra bolt length.
The driver side mount had all three bolts and nuts reinstalled, but the conical washer on the mount to K-frame stud was reversed with concave side out.
My guess is the PO allowed a class of 3rd graders make repairs to his car and in the end had some excellent examples of very bad mechanicing.
But, back to the bolt direction issue. All the unmolested 273's I have worked on had the nuts facing outward from the mount as seen in picture. I think the factory service manual actually has drawing showing this, but again, I don't think it really matters as long as you put them in.
