Gary Bobileff is the high guru when it comes to the restoration of early Lamborghinis, particularly Miuras. His shop in the northern part of San Diego County has some outstanding facilities for both service and parts.
BRC is located in Live Oak, Florida and have been making pistons for race cars for many years. They produce custom pistons for just about any application. They built the pistons in my 400GT 2+2 when I need .020 oversize and the pistons have performed perfectly. BRC is also and authorized dealer for BRC piston rings. They can match your needs for rings when you order the pistons and they will select the rings based on your driving habits.