I went with ARH 2"x3.5" headers in my 71 Nova. Proper frame stands and BBC mounts. I also have AFR265 heads. They are beautiful headers, lots of clearance for the steering box and suspension. They fit very snug to the block, I had to dimple a couple tubes to clear some bosses on the block. I also had to clearance the motor mounts.
GM PMGR starter can be taken in and out no issues, just have to slightly trim the head of one bolt to clear the tube.
Oil filter can be taken out no problem.
Drivers side back cylinder you need the snap on socket S9724RHS to remove and install the spark plug. It was designed for the LT1 engines. It also is handy for some of the other cylinders.
I would rather have the headers fit snug to the block and have more clearance to the steering box and suspension then not, which is why I say they fit well, even though I had to do a couple minor things.
I would look at the Doug's headers, they fit great on a standard head, have a set on my brother-in-laws 69 with a 402 BBC, 1.75", and they are perfect.