The stock 7/16-20 bolts that hold the flexplate to the crank are 55 ft-lbs and that's with a stock bolt. 40-45 seems way low. What bolts are you using??
I was just worried about stripping the lugs in the converter since the bolts are only 1/2" long and the flexplate is 1/8" That means there is only 3/8" of thread engagement.