Protect the exterior paint with something. Try washing the whole thing with simple green and a soft brush. Spot clean greasy areas with that purple cleaner. Rinse well and final rinse with deionized water in a hudson type sprayer. Dry well with cloths and air.

Once you are satisfied with the cleanliness of everything, treat the compartment etc with a spray on preservative/clear finishing agent and wipe off excess. You can find specialty products for the job on-line at places like Griot's and others.

If needed touch-up painted surfaces replace lines etc. Be careful not to destroy the patina on sensitive items. I remember seeing an example of ruining an otherwise amazing example of a stock engine compartment when someone scrubbed a clean spot on a 426 Hemi survivor Challenger's valve cover that effectively destroyed what would have otherwise been a time-capsule type state of preservation on the car.