I know you seen the other post I put with the brackets to bolt a b series into a 1st gen.. Since you work with fabricators, I would print that pdf out and bring it to them if you do this. Cheap though? not so much.. but not too expensive to make you never want to do it. I dont know how much you can find a good b18 for now but I have seen a couple rebuilt go for about 350-450.
As for transmission wise, Im not sure what all will bolt to a b18 but ive been told that the b16 tranny is the best to use cause its cheap, very reliable, can handle the power no problem, and has higher torqued gears then the stock b18 tranny has.. but dont quote me on any of that. Havent really dug my head into transmissions too much