Way more people on the sprinter source forum with T1n sprinter expirience than here.
MB Fresno has only been a sprinter dealer for between one and two years.
They most likely have not had much interaction with the older, completely different, out of warranty, sprinters vs. the new ones.
The model and year sprinter you have was only sold by freightliner and dodge dealers.
I'd get a second, or third opinion before I committed.
Would I recommend MB Fresno to replace the engine on a 10+ year old sprinter? Probably not without some very detailed discussion beforehand. How many engines have they replaced in vans similar to yours?
See if you can contact linden engineering in Denver to get a second opinion over the phone, he is very active on the sprinter-source forum and seems more than willing to help people, regardless of him doing the work (distance)
Bummer about the engine failure.
Where do you live? Did you drive a u-haul back home?