Please me some torque on converters

I'm the process of swapping out externally balanced 340 for a internally balanced for 408. I have 3 converters the one used on tge 340 seems to have a high stall, and the other two are supposedly stock 318 converters. I know very little about tq's, and there are no significant markings to tell these apart. The cam I'm going to run is a fairly mild Street cam rated at 1800 stall.
The converter used in the 340 seems to have extra weights
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versus the other two
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They all measure about 11 inches across
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is there a way to determine what the stall is I need to use converters?