I hope to install the motor ,(454, stock valve covers, headers), in my '67 Chevelle SS this winter. The front clip and core support will be off the car. It is a factory air car and I was wondering the best way to go with the A/C "suitcase" on the firewall. Install it before the engine or install the engine first and then the box? Don't want to risk damaging the fiberglas cover, but don't want issues with trying to work around the motor to install it either.
I would appreciate any advice from someone who has done this.
thanks.

i would think that the A/C box needs to be in place before the engine is dropped in. On the 65, I have to use stock height valve covers to clear the box - and I have to tap the engine over to get the rocker arms on #8 down to get that valve cover off. I think the 65-67 are the same.

With the front clip off. I think you can go either way.

thanks for the responses. Will probably install the box on the firewall, then get a friend to help guide the engine into place.

For what it's worth, I pulled the small block from my A/C 67 with no issues. The front clip was off when I did it. It would seem to me to be easier to install the A/C box first, then the engine/tranny. A couple extra pairs of hands will make it go a lot smoother.

I have done this very thing. With the front clip off the car, the evaporator core goes in very easily and out of the way of the motor, including the expansion valve and tubing. The blower motor case gets in the way of the engine install with a BigBlock, safer to install it after the motor is in place to avoid any scuffing of fresh paint. It isn't anything to put it in afterwards. Notice the hole in the firewall for the blower motor assembly and it's relationship to the engine in my signature coupe picture.