Yup, the 307/350/403 are all the same dimensions.
I have a 1969 Olds 350 in my car right now, but building a 403 for it for this summer. I have Headman Headers with 3" Torque Tech exhaust.
Nice car. You got a good deal if you got that for 1k. I am looking for another Cutlass to put the 350 in once I drop the 403 in my 87. quote]
How do you like the Headmans?
Im still torn between Headman and Flotech
Ive got a 307 now that evethign will be transferred to a 350
Im gona do headers into an x-pipe thru mufflers (still undecided) then tails behind the wheels