Do you want to keep it looking stock?
Do a little porting on the 093s, bigger cam and either open up the log manifolds (like this-
http://forums.maxperformanceinc.com/...d.php?t=630943 ) or install RA manifolds. A little more gear wouldn't hurt either.
A friend of mine pulled a 13.99 in his '65 GTO 'vert 4 speed- 389, 77 heads, Trips, Summit 2801 cam, RA manifolds, 3.55 rear .... and badly slipping clutch. Your '66 should be a bit lighter if it's a hardtop, the '66 Tripower flows better than the '65 and hopefully your clutch is holding.
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1966 GTO
1969 Lemans Convertible- F.A.S.T. legal family cruiser. 12.59 on G70-14 Polyglas tires. 1.78 60'
1969 Bonneville Safari- cross country family cruiser. .
1979 Trans Am 400, 4-speed, 4 wheel disc.
View from the drivers seat racing down Atco Raceway-
http://www.youtube.com/watch?v=GhYDMdOEC7A
Ride along in the other lane-
http://www.youtube.com/watch?v=mIzgpLtF_uw