Regarding the range of Laker DC-10 LGW to Orlando, I recall I did this trip as a lad once on this route, although both outbound and inbound the plane stopped for a lick of fuel at Bangor, Maine. Outbound was more efficient since we were able to clear customs at Bangor and complete the second leg as an internal flight and hence walk straight off the plane.
A few years ago on the same route I had the same occur with a 767 (not sure which version) but clearly the shorter range version since it stopped at Bangor but friends on a different airline (also 767 but different version) flew non-stop and despite having taken off 30 minutes later than me, arrived in the sunshine state more than an hour before I did! Inbound, the jetstream saved a stop!