Alright, tested it out; Fortress + Bishop by itself is very, very strong. On the 4/3, buy Bishop and silver. Get a second Bishop over the first Fortress and start trashing Estates and Coppers. Alternate Fortress and Bishop buys until you have 4 Bishops and 4 Fortresses.
By turn 12 (give or take a turn due to shuffle luck), I have an 8-card deck that can churn 12vp per turn along with 6 provinces worth in points. As soon as I'm ahead, I can adjust the deck in one turn by Bishop-ing a Bishop to make 8vp a turn while draining any and all 3 or less cost cards. In essence, this could indeed be (and I would go as far as to say 'is') much stronger than the original golden deck of Bishop + Chapel.
NOTE: I tested this with the normal starting deck. With shelters however, I'd assume it would go a bit smoother since Necropolis can alleviate the possibility of the first two Bishops colliding, not to mention the +1 card gained from Overgrown Estate. Buying the Estate on $2 with Hovel wouldn't hurt here since you're not going to buy Provinces or Duchies anyway, and you can trash the Estate for an extra point.