Chassis width

I'm building an FC chassis. In my drawing, it says that it it should be 17 "from the ground-tubes and 18" between the upper tubes. I plan to use starter and then it will low on space. how does it affect driveability If I widen the chassis

 

My customers always seemed to like an easy to work on car, nothing to do with a starter, but my cars through the years have always been 18-7/8" inside bottom and 19" inside top at motor plate. Even has the novelty of having a place for your feet to be!

Bob Meyer
Meyer Race Cars / San Diego
2013 Our 48th Anniversary