I have built arrows from both parallel shafts and the AD shafts. Each has its own place. I think the first question should be why are you wanting to build EFOC or UEFOC shafts.
I have been active here when Ashby's stuff came out. It can be beneficial with the right bow for special needs on large, heavy hide and boned game. If thats your requirement reason pleas tell us. FOC of 20% is good enough.
OK, so lets say you need these arrows for large thick skinned beasties. I would, as has been said above, start with something about 400 spine in a parallel shaft or in the case of AD shafts 325 in the Hammerhead or 350 in the Stinger. There is a listing for X-lite at 7.8 gpi for that arrow. Be sure, if you order from AD you request the highest priced shafts. These will be the straightest and closest in weight shaft to shaft.
Now the fun begins. You will need to "tune" these slowly to your bow and your form. This can mean adding weight up front while shortening the shaft. On the AD's I always shortened from the front and added weight.
A heavy arrow on a 45# bow will lose flight pretty quick (my experience) after about 20+/- yards. You need to make the choice.
Just my thoughts.....