I have a 1990 CRX Si, and i am going to put a new engine in very soon. i want a b18, but i'm not sure what the diff. between the b18a, and b18b are etc. what would be the best engine to put in? also i need to know where i can find a b18 engine to purchase and a shop that does good work to install it. what are some good shops that will install it? All advice is greatly appreciated.

Thanks, 90_CRX_SI