Herter's Aluminum arrows

[Stinger]

I have a couple dozen Herter's aluminum arrows cut to 28 1/2 inches that weigh 420 grains without a point and spine out at 73 on the spin-o-meter.  The arrows have adapters for glue on heads.  I would like to use these on my lighter setup and was thinking I could reduce the spine by using the PDP weight system from 3R, but have no idea what the shaft size is on those arrows.  Does anyone know whether a 5/16 or 11/32 adapter will fit those arrows?  My thinking is that if I can get the spine down to a 45# draw weight by adding 100 grains or so + a 125 gr head that I end up with a pretty heavy arrow with good FOC.  It won't go very fast but should get good penetration.