Hi,
T1275 you say? Used? Hmmmm amp hours of capacity for each of your (6v x 2)?
Your bank of sixes is already balanced yes?
I would feed the t1275's into a common bus with the bank of sixes after wiring them as method #2 from the smart gauge site.
if the t1275's end up being more like 115 amp-hours each (allowing for age and abuse) I'd rewire using method #3 for two six, two six, and two t-1275 (with the t-1275 made into a single batter via method #2)
+xxx xxx- (two sixes) (232 amp hours) bat 1
+xxx xxx- (second set of sixes) (232 amp hours) bat 2
+xxxxxx- (t1275)
{......} (pair = approx 232 amp hours) bat 3
+xxxxxx- (#2 t1275)
feed to a common bus with equal length cables for each individual bank.