FWIW we have 1/4" of shims between flexplate and convertor on the camaro in sig. Turns 7200 RPM on a routine basis, stressed it to 7500 rpm today.

 

i have only done chrysler flex plate 3-4 times. all being the older ones. but if every thing is ok when the engine is bolted up there is some gap between the converter lugs, and the flex plate. you just pull the converter forward to the plate, and bolt them togeather.