Rear cross member after you get the front motor mounts seated. That is my preference. One less thing to fight. You may need to lift the rear of the transmission to get the motor mounts in place. If too much of an angle they may not go.A Chilton or Haynes manual can be helpful as it gives a step by step approach. I am sure a web search will do the same.
I am hoping to install my engine/trans combo as soon as I get my oil pump in the mail
Do you guys have a preference on using either a plate attached to the intake at the carb location OR using a chain bolted to the front and back of the motor? I have always been skeptical of all that weight being suspended from four bolts into an aluminum manifold. I see it done so guess it is ok.
Also, will the engine/trans combo go in easier with the transmission crossmember installed or is it easier to get the combo in place, raise the back of the tranny, then slide in the crossmember?
sorry to hijack but figured these questions applicable to the OP.