A few practical considerations prevent making effective use of your idea. We would LIKE all our restored equipment to be housed in an (unheated) barn but funding to accomplish that is lacking. SEND DONATIONS.
For steam locomotives, a restoration may result in a locomotive that looks good as a display, but that restoration is 'perishable' as far as operations. As soon as the FRA inspection passes, the clock begins ticking on expiration of a number of components whether the locomotive is operated or not. So, if you had as many as a dozen operating engines, and rotated one in and out of service on a monthly basis, many would get little or no use before demanding another infusion of funds.
A number of comments have formed a thread without directly being related to a topic, here. The work in the several IRM shop areas always needs volunteer help, but I would encourage you to contact the shops or departments directly through email or other means to know that work will be waiting for you and be organized to the extent possible. There is no way I as an individual can know what might be waiting in the Wood Shop, Diesel Shop, Freight Car Department, Electric Car Department, Buildings and Grounds, Operations, Coach Department, Steam Shop, Electric Trolley Coach, etc. I know Greg W but we have not crossed paths in several years.