Nice looking boat Rye, though it has a minor problem. PT-84 was a Higgins boat, not an Elco.
78' Higgins Motor Torpedo Boat:

Laid down 5 May 1942 by Higgins Industries, New Orleans, LA
Launched 7 September 1942
Completed 3 December 1942
Placed in service 7 December 1942
Destroyed by U.S. Forces 23 November 1945 at Samar, Philippines.
Specifications:


Displacement 56 t.
Length 78'
Beam 20' 8"
Draft 5' 3"
Speed 40 kts.
Complement 17
Armament: Four 21" torpedoes, one 40mm mount and two twin .50 cal. machine guns
Propulsion: Three 4,500shp Packard W-14 M2500 gasoline engines, three shafts

Since your boat looks like an 80 footer, one of the following hull numbers would be better:
103-196, 314-367, 372-383, 486-563, 565-624 and 791-808.
All of this info is listed here:
http://www.navsource.org/archives/12/05idx.htm