safe to lift engine using intake manni bolt holes

I would be concerned as well. However, I know of those that do it.

The head to intake manifold sealing surfaces require a smooth finish for a leak free result.

I am sure you are aware of the boss holes on each corner of the heads made for lifting? The Windsor heads use an M14, the Romeo uses M12. The bosses are in the front left and back right.

It can be difficult attaching the leveler using the head bosses. The valve covers need to be protected. If the bolt sticks out too far on the back right, it will interfer with the AC hard line.

Of course if you are willing to take the intake manifold off, then the valley front/back webbing makes a perfect attachment point. Down side is that the intake manifold would need to be installed while the engine is in the car.

Should be fine, I have seen it done. I try to just use the most solid point on at minimum 2 opposing corners.

Lay some duct tape, blue tape, whatever across the intake ports on the heads. You should have done this already if you havent. It will keep **** from falling into your heads, and will provide some protection against the "marring" you were concerned about.

Question? At the time you are installing the motor will the Intake manifold be installed? I am assuming that the automatic transmission is still installed in the car.

If the intake is NOT installed, I would have to wonder why the valley webbing is not being used. There are 4 perfect lifting points. Two in the front where the alternator attaches and two in back.

Please ignore the above if the intake manifold is on the motor.

Since the transmission is already in the car, the amount of engine tilting needed is little if any. An option is to use the front valley webbing (alternator attachment) for the motor front. For the engine rear run the strap through the exhaust headers and under the oil pan. This will minimize the chances of the stap slipping off of the rear of the oil pan. This method has the advantage of fully supporting the motor without stressing the small exhaust manifold bolts.