Ted;
Yes I am quite certain the 707 was built to Mr Sell's specifications. Mine had the slight over-bore & 1" forcing cones that he championed. I seem to recall him writing about one of them he had with 30" barrels & he stated it weighed 6 3/4 lbs. Mine had 28" barrels & I weighed it on what I though at the time was an accurate set of scales & it only hit 6 lbs. Those 1 1/8pz loads I mentioned were rather comfortable from it but for much of the full 1 oz loads I would prefer it at 6 3/4 lbs minimum. You start getting up around 7 lbs you may as well have a light 12.
I no longer have any desire for a 3" 20 nor one weighing in at much over 6 lbs. I also have no desire for a 28 if it weighs more than about 5 lbs (5 would be even better) nor for it to throw more than 3/4 oz. Beyond that & that's what the twenty is for. I liked the old "Heavy Field loads of 2-1 in a 20 or the 2 3/4-1 1/8 in a 16. Heavier than these I'll still take the 12.