A very nice page of specs ....
http://members.rennlist.com/pirtle/s4atrans.htm
Edited ***
Ratios A28/16 A28/the rest
1st gear 3.87 3.676
2nd gear 2.25 2.4120
3rd gear 1.44 1.436
4th gear 1.00 1.00
Reverse gear 5.59 5.139
Final drive ratio
15:33 i = 2.200
14:33 i = 2.357 (A 28.05/08)
13:33 i = 2.538 (A 28.06/09/11/14/16)
Stall speed
A 28.04/07 = 1650…2050 1/min
A 28.05/06/08/09/11 = 2200…2600 1/min
A 28.12 = 1750…2150 1/min
A 28.14/16 = 1750…2150 1/min
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Have you checked the current stall speed?
I wonder if you could use the earlier higher stall converter?