Are you roasting or rotisserie grilling this meat....also, will the bone still be attached?
My best advice is...learn how to slice or carve properly. also, you are going to need more time than 6 hours, unless you do not mind serving shoe leather.
From the Internet: Google Alto-Shaam Steamship Roast.....
Proper preparation of Steamship Rounds
Chef Michael Salvatore
As the steamship round is not usually a weekly offering…a little reminder on proper cooking:
1. Preheat oven to 350ºF
2. Season heavily and stud with garlic cloves. Place in roasting pan or square-head standing up, not lying down.
3. Allow roast to temper at room temperature for one hour prior to firing
4. Cooking time will be 12-14 hours depending on final weight. Alto Shaam up to 16 hours @ 350ºF.
5. To check doneness, use a bi-metallic probe thermometer or thermocouple at the thickest part of the top round side of the roast. Push it all the way in to the dial. The roast is ready when it reads 140ºF at that depth.
6. Allow roast to rest, loosely tented with foil, for at least an hour before sending it out to the buffet.
7. If brunch starts at 11:00 on Sunday, it must be out of the walk-in by 7:00 PM and fired by 8:00 PM Saturday night. It will hold for hours so earlier is better than later.
Quite an undertaking!
I only have one tidbit that we used to use when we were roasting whole top-rounds- rather than use simple salt and pepper, use beef base (knorr's paste). it is intensely salty on the surface, but the juice that runs off will be intensely beefy and is great for basting the steamship and will save you some time making a finishing sauce.
Other than that: Big Oven, go low and slow, don't lift it by yourself!
(Really? A Whole Steamship!)