First Engine Build - Advice Needed

You could disaasemble, check clearances and do an "Overhaul" This is assuming that your crank journals aren't scored, and you can hone cylinders and re ring. All it takes is cleaning the parts up and taking measurements. If there is a heavy ridge on the cylinders, that may be a sign for example, if there is no ridge, it may be good to go. But you would measure taper by measuring ring gaps, top and bottom and subtracting the two. You could measure the cam lobes for wear. As you do this, you take notes. Ideally all you would need in parts is a gasket set, and a ring set, maybe a cam. If you cam it, you may want to get a good carburetor, the sky is the limit. My point is, you can get away with not going to a machine shop if it isn't warranted or necessary based on your clean/inspect/ take measurements process. It is a 383 so it should be plenty of power for a Valiant in stock form.