Marc,
Couple of suggestions.
Number 1, analog gauges are accurate to +/- 20%, so your 240 degree reading might have only been 192 degrees. If you don't have one, get a non-contact infrared thermometer with laser targeting. That will be much more accurate than your analog gauge.
Number 2, get the Silverleaf VM Spc monitoring program. It will run you $300 for the cable, but the program that runs on Windows 7 is a free download. Here's a post that has the information you will need :
http://www.luxurycoachlifestyle.com/...ead.php?t=4665
I lost my 8V92 to overheating, and it's not inexpensive to fix. I decided to take the engine swap alternative, and still negotiating getting a Cummins 11L ISM and 6spd ZF transmission installed in my coach. Was able to pick up the donor coach, but currently having a problem finding a reputable shop in my area to do the work for a fair price.
good luck,
jon