Ya, its a tight fit.
Im running a 383 in a 67 barracuda.
I find that when i was going thru the installment process it was easier to put engine and trans, bolted together, in through the bottom of the car.
It can be a circus of using the engine hoist to raise the car, with the engine/trans on a home built dolly. Once you do it this way, you might never go back to the old way.
Nice lookin dart BTW!