Well, I just bought a 91 Si rolling shell for 250 dollars. Now, I just have to find a motor to put in it. Looking to run pretty quick but I want to keep it NA. I have been thinking of doing a B20Z w/ GSR Head. Would I run into any issues using the stock B20Z bottom and the Stock GSR Head? Would it be less headache to do a B18B bottom and the Stock GSR Head? Any help would be appreciated. Thanks guys!