Lateral-g Forums - Setting engine/trans angle?

I’m in the process of modifying my transmission crossmember on my 68 camaro for my swap. I’m using my stock front subframe and the car is currently empty except the motor/trans and rear suspension and no front sheet metal either. With the car sitting up high with the lack of weight what would i use to help get a desired angle on the motor/trans? At this time I’m only worried about the motor/trans angle, not the entire/final driveline angle. Would i use the subframe as a zero degree reference? By the way the car is sitting on all four tires.