First thing to remember, alot of guys on craigslist will say anything that puts money in their pocket.
2nd, longtubes are a pain... period. The only longtubes that go in easy are the multi-piece ones, and they ALWAYS leak.
3rd, MAC headers are crap, even their unequal shorties are a bitch to install. Individual flanges that just don't quite line up. Uhg. BBK... ALL THE WAY! They're affordable, they fit beautifully, and they last forever.
I just put Mac long tubes on my car a few days ago, and I have to agree, they were a major PITA. They were a replacement for BBK shorties, which were always very easy to install. I had to jack up the engine and unhook the steering shaft. All that is to be expected with long tubes, but bolting them to the heads was the real pain. They are in now and everything is bolted back up but the passenger side is right on the k member and the drivers side flange is touching the floor under the car, so I still need to figure that out. I am looking at the motor mounts for that problem. If I had to do it again, I would pay the extra 40 bucks and get the BBK's with the one piece head flange. Live and learn.
longtubes are nice if u got a tubular k-member...there a pita to install with the stock one my buddy has bbk ones and he had clearance problems with the steering shaft headers were hitting it....there only nice for tourqe..but a pain in the ass