Personal experience-
Bob mazzolini 440 A body headers-

I think these are headman B body headers. They fit with with plenty of clearance dents added with the big hammer. including flattening the passenger side inner fenderwell with a sledge at the shock tower. Plug clearance with stock heads is ok. If I remember correctly they are 1 3/4" primaries.Changing plugs will take an afternoon unless you cut some acsess holes in fenderwells.

CPPA headers-
2" primaries, industrial chrome plated.I believe these are the same as modern TTI headers. These headers burned the boots of every plug wire and shield I tried with the exception of Jacobs wires with the ceramic boot. Switching to edelbrock heads cured all plug wire issues. The down side to these are that they totally encapsulate the starter. Want to change it? the motor is going to have to come out. when the motor goes in, the starter better be in the right position. If the body has rotated a bit too much and you get the motor in, you wont be able to spin the starter into it's correct position without pulling the motor back out. I've done all my motor installations by myself hanging the headers and starter roughly in place with safety wire. If you have a helper I'm sure you can knock a few hours off of the installation time.

Pro-Parts semi fenderwell headers-
The answer to everyone's prayers that has had underchassis headers in an A body. 2" primaries, can be installed or removed with the engine in place. Starter can be changed out without drama, even at the track! No issues with tires and turning. Ground clearance is almost the same as the CPPA's. Headers that assymble in one and two tube sections are the way to go as far as i'm concerned.
On the downside, at least for some, the headers require holes in the fenderwells. Of course so did the underchassis headers if you want to change plugs in less than a day. These holes just have to be bigger.
-Tom.