Take the hood off and move the fenders in so the sides are in-line with the doors. Narrow it up in the front. Otherwise you'll need the door pieces to match the fenders off a 42-48 Chevy/Olds/Poncho - or even a Caddy. Or you could run the pipes out the fender holes.
the rest of the Buick is at The Yard! LOL thinking of pulling the fenders forward drop the hood maybe funny looking Cord type thing[SI'll mock something up an get some pics
Sam they look alot like that little more curve at the rocker, here is what I'm thinking .use the door pieces for fiilers[now what to call it? be nice!!!lol and move to the build page[cl