How to Calculate Lifting Capacity of a Partially Engaged Lifting Eye Bolt

I would like some help calculating the lifting capacity of a partially engaged lifting eye bolt. The specifics...

We have a part that weighs approx 1,100 lbs and has three threaded M12x1.75 holes that are 11mm deep. The holes are on the top of the part and the eyes would all be lifting by chains in the vertical postion.

McMaster Carr sells a lifting eye bolt (part # 3040T15) with a capacity of 2,270 lbs and a threaded length of 24mm. The hole actually is 17mm deep but only 11mm is threaded. I would like to cut down the bolt to 16 mm so the bolt shoulder engages during the lift. I'm not sure of the bolt material (the specific steel grade) but have emailed McMaster requesting this info.

Is there a formula I can use to calculate the lifting capacity of this reduced length lifting bolt? I had been trying to manipulate the following formula... but I'm basically stuck. Thanks.

LE = [Allow Tens / (Allow Stress)(TSA_I)(N)]+(1/N)

Edit Note - I would use all three holes to lift the part. We typically design lifting devices with a factor of safety of 3x or 4x the actual weight of the part. So if the part weighs 1,100 lbs we deisgn it to 3,300 or 4,400 lbs depending on the situation.