I recall a discussion which suggested that the original design called for a T-tail
Yep, the design grew out of the Demon and Banshee and at one stage ( as the F3H-G/H, which
AFAIK only existed as a mock up) it did indeed have a straight T- tail.
subsequently changed as that configuration wouldn't have made the cut for carrier operations.
Only references I can find for the reasons for the change to anhedral in the final design (Dorr, Boyne) discuss that there was a need for a low set tailplane but there being no room for one given the rear fuselage shape/ jet pipe position. The solution was to use a large degree of anhedral.