Circle d torque converter in a 4l80e/lq4

[Slowguy]

So I’m ready to plop the 6.0 onto the frame. The only thing that’s holding me up now is that I can’t get a straight answer from circle d (or I’m just too ignorant to comprehend what they are telling me).

I bought this converter: http://www.circledspecialties.com/4l80-hp-series-278mm

After I get it they tell me I can’t use my stock flex plate and that “any” plate from a 4l60 will work. I ask the specifically and they continually point me to new aftermarket $240-500 options. Had I known I’d need a $250 flex plate i’d Probably not done the converter.

Can anyone tell me specifically if there is a used plate I can buy? 5.3/4l60 plates are a dime a dozen on eBay but I want to make sure I’m getting something that’s compatible with both this circle d converter and my lq4 crank. Also, aren’t the plate balanced with the rotating assembly at the factory? If my engine is done, how would a used plate affect the balance?