273 to 440 swap

I've done both and neither is really harder than the other. There are just different clearance issues. The RB will have more issues around the master cylinder and heater blower motor. Running B-body HP manifolds will give more clearance issues at the right inner fenderwell, but none of this is insurmountable. As always it is easier to get the drivetrain in with the steering column out of the car along with the heater box.