A few responses:
1. Explosiveness is good, and in fact a good reason to even consider running a non-Blue deck in Legacy, given that you then miss out on counterspells and cantrips. Mox Diamond as a ramp option is a good card to take advantage of running a higher land-count and LftL, and will help you drop stuff earlier like a turn 1 Chalice on 1 -- a play that often yields victory against quite a few archetypes.
2. That said, I don't think you are gaining all that much by adding Punishing Fire to your deck. You are destabilizing your mana base in a pretty major way to become a weaker version of existing decks. And for what? A card that helps against smaller creature decks? You already have access to cards like Toxic Deluge, Liliana, and it seemed like your original goal was to utilize Ensnaring Bridge. I just really don't think PFire is doing all that much for you that can't already be accomplished with the original idea of staying in BG. My suggestion for dipping into a third color was more along the lines of running a Dual or two to splash into things like Ancient Grudge in the sideboard. And besides, if you want a Loam-enabler Red card that's amazing against creatures, consider
Devastating Dreams. But you can stay in BG and still have access to repeatable removal, e.g.
Cabal Pit or
Cursed Scroll.
3. Dropping too much discard is going to make you especially weak to combo. If you can't have a decent shot against at least a few types of combo decks, your deck is definitely going to be Tier 2 at best. My assumption is that you're trying to construct a fairly competitive list, right?
4. Given your fairly high density of Artifacts, perhaps the direction you're going into is something more like UBx Tezzeret? I would at least check out that deck's thread to see some of the options those players have discussed, since there seems to be a fair amount of strategic overlap here.
5. Regarding the Wish board: I know you were probably thinking about Burning Wish, but consider Living Wish as the Green alternative: it can snag you creatures and lands, which provide a full tool-kit of answers to various problems.
6. No matter what choices you ultimately make, you need to consider the Win Condition(s). Decks that don't run enough win conditions tend to do poorly -- you need a fair number of cards that can decisively end the game once you've established board control. Creatures do a pretty good job of this and can simultaneously function as disruptive elements, and BG(x) provides plenty of good options. I know you're thinking of running 4 Chalice in the main deck, but even so you might still want to start with 4 Deathrite Shaman. Any non-combo Golgari deck needs a very, VERY good reason to not be starting its list with 4 copies of this card.
edit: If you're
really crazy about Sadistic Sacrament, perhaps BR(x) is the starting point -- that way, you also get access to
Slaughter Games, which is arguably better anyways. There are a fair number of powerful Rakdos cards as well. So maybe going an entirely different direction, perhaps
without Green is worth considering.