Just a thought, Have you considered looking for a silver 6V92 turbo if you are doing a swap? Don't know what the logistics is, but it is a really nice upgrade if you are paying for another engine anyway.
Can't help on the replacement engine but something I've done to read an inaccessible serial number is to drop a digital camera in and take multiple pictures.
I have one of those fan set us on a 6-92 but the block is busted. I do have a LH 6V92TA DDEC III setting here with about 225 hrs. on it I don't think you would want to spend the money to convert it to an mui. Clifford may know where one may be.Sorry I can't help.Don
Serial number indicates mid - late 1973. www.arb.ca.gov/msprog/moyer/guidelines/detroit_diesel_1972-1993.pdf
Sweet! I'm a mid-1973 model too! - Cherie