first thing to consider are the heads.
stock smogger sbc head will max out about 400 hp no matter what size engine is under them. The difference will be the bigger engine will make the max hp sooner (more torque).
so, I would rather have a 355 with a good set of heads than a 434 with a scrappy stock set.
The next thing to consider is the strength of the block. I would limit the max hp on a stock block to 600hp. so neither build a 500hp 434 with a 100 shot or a 450 hp 355 with a 150 shot. The results will be very similar at the track.
The advantage the 355 would have is the cost to build and slightly lower piston speed at the same rpm.