LH suitability is your ability to demonstrate effectively that you can operate the sim which in this case is 744 to a high standard.By this I mean close to LPC standard.It used to be 2000hrs but the process has evolved.
The assessor has to ask himself will the candidate be able to cope with maybe just two or three landings a month with extremes of weather possible.If in doubt revert to SH until they have built up enough competency to cope with the aforementioned scenario.