I'd go for the TacRL.
I often try to get one for the Armory, since it makes shambler's head easier (and getting it tends to give you a nano, which is neat).
It can never be guaranteed, but I don't see much use for those (great) B-mods anyway. My next ones usually go on a plasma gun (which I try to make nanomachic), then on BFGs (which barely ever use, but big BFGs are cool, and makes me comfortable)
You might also consider the gatling gun, which is great. I stopped crafting it since I reserve my B for tacRL & my plasma gun, but it rocks.
The only sad thing is that it's a sort of plasma gun... with bullet type damages. Which is a bit weak. On the other hand, it's usually easier to find a bunch of bullets.
The other assemblies seem pointless to me, since a normal weapon with 5 mods will often be just better than a dubious assembly.
I don't remember well. Was the movement penalty for bluk-modding armors removed in 0.9.9.7 ? If it wasn't, I wouldn't advise to do it.
Fireproof can probably be a good armor, but I forgot about it due to its lack of versality, since some (maybe too good) stuff exist, and don't have such drawbacks.
Putting B on chainsaw is cool, but I doubt it's as useful as it should be, since BRU/BER give you insane damage boosts already anyway, and the AoD basically requires either great speed, or crude melee power, which kinda both make the damage difference unnecessary.