this topic has been covered a couple of times. The b20b is a horrible base to start on for FI or high revving NA.Im not saying they blow up all the time, but if you are building a high output b series, your money is better spent getting a resleeved ls block or start with b18c, whitch have shown to withstand alot of punishment. The b20b, imo, is nothing special, it is basically an ls with 84mm bore with weaker sleeves. i know your question was towards vapor, but its also very broad...

what kind of hp you have in mind? whats your budget?