Grinding or roaring noises when turning could be wheel bearings. When you were doing the engine swap, did you at any point roll the car forward or backward without the axles torqued into the front wheel spindles? If you did, you more than likely damaged the front wheel bearings. Check all 4 wheel bearings, that could be where the grinding sound is coming from.

The clunk in the steering rack could be tie rod ends or a bad ball joint. Ball joints can clunk when they get old and loose.

You can't judge an axle by its look. Could look clean and shiney but be totally junked. Axles will make a clickitty clickitty sound when turning if they're going bad, but it won't sound like grinding, like you described.