Help me decide - which air cleaner ?

Here's another vote for stock. As long as you've got enough snorkel cross-sectional area to equal or exceed the total cross-sectional area of the carburetor's venturis, you'll have no restriction. The snorkel type air cleaner is a much better deal for driveability and performance; you get warm air til the carb's warmed up, then you get cool air. Those open-element air cleaners suck up barbecue-hot engine air all the time. They sound meaner, but that's their only advantage.