Engine rebuild

I have the Demon in the shop for minor restoration work and the mechanic needed to get a new timing chain as the old one was stretched for being raced too hard. If I get the engine completely rebuilt will this be detrimental to the numbers matching engine and transmission? It is not dead, but does have 155,000 miles on it and I do not want to hurt the numbers value. So, If I get the engine, transmission, and rear end rebuilt will it lessen the value of the numbers matching car?
Thanks,
D340
Author: admin