Chris Craft 501 on the Great Loop.

The primary issues are draft and air draft. You are not talking a length that should present a major problem. As to speed, you will have areas of displacement or near displacement speeds but there are also areas in which you can go faster for a period of time.

Transients often are not in slips but side ties. Regardless, that beam shouldn't be an issue.

I just came from Lake Michigan to the Gulf with a 56 Hatteras MY and had no issues at all with depth at 5'2" or the 18'2" beam. We have a hydraulic arch and took the Bimini down for the 19'1" bridge in Lemont, IL and found we had more than 19'1" clearance even though we didn't need it.

We're behind RD480, also with a 56 Hatteras MY. We've run from NY down to Charleston, back up and we're now wintering in Michigan. With the arch down we have an 18' air draft, and we've had no problems. Our spec shows a draft of 4'10". The only place we ran into problems with that so far was in the Carolinas. We grounded once at Shallote Inlet on the ICW, but no big deal. Just put the bow into a shoal, and waited for the tide to come in a bit. With our 18'2" beam and high sides we always seek side boarding and haven't run into any problems, although we're running a little behind the crowd. On the way to Tobermory up on Lake Huron we've been cautioned about a few of the ports some smaller boats go into, but that was a minor adjustment. The one caution I would give is the Trent-Severn. We decided to pass on it and come through the Welland Canal instead. Cruising all day with one eye on the depth finder through the Carolinas was enough that the boss didn't want to do it again on the T.S. where the bottom is rock.
As pointed out, there are places where you'll be running at dispacement speed and places where you can open her up. It all works out. Probably the biggest problem we've run into is with shore power. There have been many places that suppy only 190v to 208v and sometimes less. This boat draws a lot of juice. At many docks we've had to run out (2) 50 amp cords and split the load. Even with that we often pop breakers when the air conditioning, water heater or clothes drier kick in. You'll also find many places in Canada that only have 30amp outlets. So have Y splitters.
One thing I will mention is that a 50 footer is at the big end of most doing the Loop. Just be sure to reserve your dockage before heading for a port as dockage may be limited for that size depending when you come through.

Libertonia,
Did you end up purchasing a 501?