Flightomatic questions

A PO of my 60 Lark convertible replaced the original 259 and Flightomatic
with a 57 289 that is buttoned up to a 6 cyl. taxi Flightomatic. This is
the "green tag" AS 2-7E transmission that is listed for the 59&60 Y bodies
(maybe others). I don't know which torque converter is in the car: the 6 or
the V-8, however the car seems to bog down under certain accelaration
conditions. The trans and engine both operate well but leak badly so I'm
considering pulling both to address these issues. The trans has a first
gear start and the tires chirp nicely on the 1-2 upshift at full throttle.

My questions to the group are:

1) Is the 6 cyl taxi transmission inherently weaker than the V-8
Flightomatic? If so, could it handle the torque of the 289 under normal
use?

2) If the torque converter in the car is found to be specified for the 6,
would changing to the correct 8 cyl converter help performance?

Frank Philippi