I've not done this with a TR4/TR4A but have with a TR250 and TR6. This is the procedure I use.
The bonnet gets removed, the car goes up on stands as high as it will go, the front wheels get removed that then lowered onto stands until the brakes are just above the floor and the legs of the hoist clear the frame. The engine/transmission (transmission top cover on, shifter removed) unit is chained and then lifted so that it is level when lifted. While an assistant guides the output side of the transmission over the front of the car, the hoist is pushed toward the rear of the car. With the dash support removed and the transmission tunnel cover removed, it pretty much a straight shot back with the combined units. Again the assistant guides the transmission output side to ensure that body work is cleared and then the combined units are slowly lowered with the assistant guiding the transmission onto the transmission mounts and loosely installing fasteners. The engine is then slowly lowered onto the engine mounts and fasteners loosely installed, the hoist hook is removed from the chain and the hoist pulled back. The car is then raised to be level on stands and the hoist hook attached to the lift chain to get the engine to final position and all fasteners torqued to spec.
While I have a leveler for the engine hoist, when possible, I have found it easier to angle the car rather than use the leveler to change the angle of the combined units for removal and installation.