Late A headers on an early A (smallblock)

Ok once again as the original post goes.
Where are the tight spots using a late headers on an early A? My car has a 12 point cage and no inner fenders so I have some extra real estate. I already have a set of SB A body headers, a chop saw and a welder so moving some tubes is no big deal, I just wanted a bit of info before I attempt it. The 360 I want to kill needs to breath through something a little larger than manifolds and once the 360 is dead, an RB motor will be taking it's place. So if you have condescending remarks, Oh i don't know what it is but it makes sense to keep your comments to yourself.