Engine bay aesthetics

I'd use TMM's engine bay as a great example to follow.
Biggest difference I see in 'stuff' is the coil location.

Use the factory spark plug wire routing or something close. They routed it and used seperators to minimize one effecting another. Long distances of parallel and close can contribute to misfires.
If you don't want to modify the cast valve covers, at least a couple companies sell wire holders held by the valve cover screws.

Ground strap. The 2nd gen 60s cars had the engine to body ground in the back of the engine. Later cars have battery to body ground wire as part of the battery negative cable. Generally having both does not hurt. Anyway my point was you could move to the rear to clean things up. Flat braided grounding cable looks nice, or a black insulated 10 or 12 ga wire would blend in the shadows.

Engine bay harness can be wrapped in non-sticky electrical tape (or convolute if you like). Its taken me a long ime to come around to this but the factory route is actually pretty good. It keeps the wires away from heat and supports it to minimize stresses on the connectors. Again without drilling the cast valve covers you'll just have to be creative in ways to support wires up off the intake.