The Ford engines are longer than a comparable Chev engine, but I see a lot of model A's running Ford engines. I do know that the cab is incredibly tight on a model A truck, and for every inch of firewall recess that you have to put in to accomodate a long engine, you pay a big penalty in foot room. That being said, I think that pound for pound, the 289 mustang engine makes a lot more power than any Y-block.---as far as being too narrow, I don't think so.