[jimcarry]

1.)Plug and Plat would be a no you just wont get the kind of coverage you need for this job.
2.)The motor will have to be taken part to prep each piece to be plated .
3.) The paint must be striped you must sand and polish until the pieces are nice
the best finish you start with is the best finish you will end up with .
4.)For the high temps of the manifolds there are coatings that can be applied to the inside
to help protect against heat also a good heavy coat of copper on the outside befor the chrome is applied will help protect against the heat .
5.) You must dip these parts to get the finish you want !!!!!
Good Luck