I missed this the first time around, too. If you are really trying to do a Baltic Porter, then be prepared for a strange animal. It is very little like other porters. It's sort of like a big Brown Porter, but with more dark fruit charcter and complexity.
Don't include both Special B and 120L crystal. They are too similar here and, as BIRD said, will probably muddy each other up more than compliment each other. The 90L probably is fine, but I do not know how necessary it is. It could wind up contributing some nice toffee or nutty notes, though. The 60L probably is good for some caramel sweetness, which you'll need to balance out everything else.
I don't think you need any roasted barley in this at all, unless you are trying to get something roastier than a typical Baltic Porter. Even still, I would recommend more chocolate malt than any roasted barley, maybe a half pound or 10 oz. Chocolate malt will get you the roasty notes, but it will keep the beer rounder, where the roasted barley is sharper. In fact, try to find the Carafa Special (dehusked) malt or dehusked chocolate. That will work much better. Keep the black patent far, far away from this beer. It has no place here.
I highly recommend shifting your malt bill more towards Munich and away from pale malt. That will add some sweetness, as well as some bready and toasty notes. Really, I would go with all or nearly all Munich for the base malt. There is nothing wrong with combining light and dark Munich, either. If you don't like that much Munich, consider Vienna instead of pale malt, or maybe some Pilsner. This really is a continental beer more than a British one.
Take it easy on the hops, whatever you do. Let the dark malts and mild esters do the talking here. Keep the IBUs way down to about 40-50% of your OG, and only have the slighest bit of hop flavor or aroma, if any.
Ferment on the high side with a lager yeast or on the low, low side with an ale yeast. THe lager yeasts tend to work better here. Like I said, it's an odd animal.
TL
