In consideration of restoration, a close examination is necessary to determine the extent of need to effect a satisfactory return to client. This determination is first outlined by the instrument and its condition and also to the intent of client and expenditures. If the structural elements are deemed worthy, then attentions can be delivered to the mechanicals and thereafter finish aspects can be considered.
Many times a piano will have a "sentimental value" having been passed on through the family however this value is best set as a realized finite point in that some instruments are not worthy of considered costs and a replacement selection may provide the best option. Once an appraisal is effected the rebuilder may then present their opinion regards recommendation of work to ensue. The client of course shall be informed of any options or preferences so that a successful conclusion will follow. Due to the amount of time to rebuild, a replacement instrument may be supplied by the rebuilder. A formal contract describing the inclusions of responsibilities, a time element and payment terms is drafted and signed by both parties. The integrity of all parties and the reverence to the work are best established at the onset of the agreement so that each principal may commit willingly to process. A full restoration includes installation of a new soundboard, pinblock, stringing, complete action attentions (replacements) and the refinishing of the cabinet with its attendant  appurtenances (hardware, bench etc.). These costs vary from $15,000 to $40,000 based on the involvement of repairs, needs of client, size of the instrument and logistics. The selection of the rebuilder dictates a position of trust. Thus a professional presentation of person, experience and wares assures  a certain compatibility. Money and value do not equate on a par basis. 
Serious consideration by both parties is required. References upon request is reasonable. All this being said, the endeavor of rebuilding a fine piano is quite worthy, the costs of which are considerably less than the purchase of new. This is a noble pursuit which provides an increase in the human condition and demands serious and deliberate intent.