California Flash
A benefit of the out of the car component test fit / run in is you can easily see where clearance issues might arise and rectify them before flying hammers and swearing become the fix.
I have read about clearance issues with header primaries and the power steering box and the steering components. This combo had the header resting on the box and the steering arm too close for comfort. 3/16" shims were placed under the insulators solving both problems while still keeping the engine level. When the engine goes in the car, it will get 1/4" aluminum plates / shims between the K mounts and the rubber insulators.