Very interesting.  I wonder what the gain or loss would be on our cars.  I assumed that with the technology in ours being 30-40 yrs old you would get much better air flow with a better air intake/filter system.  

Check this out. http://www.hotrod.com/techarticles/engine/hrdp_1105_leaf_blower_supercharger/

My Gawd, you gotta love this internet thing!  That's it, I'm buying a couple or 4 leaf blowers!

To me, you only benefit from a low restriction air filter at high rpm.  We don't operate our cars near redline.  I could see getting an AEM Dry Flow just so you don't have to buy any more paper ones and you don't have to oil the Dry Flow.

I'm just sticking to stock air filters on my daily drivers.  I took the K&N off my truck after I looked at the MAF sensor in the intake tube.  Oily film on it and I didn't over oil the filter.

Heads heads heads!!

Horsepower is for bragging...torque is for driving. That being said....are you looking for top speed, or just more 'round town driving grunt? Top speed has more to do with horsepower, while bottom end, off the line performance is mostly torque related.
A good intake/carb combo, and a nice set of headers with free flowing exhaust system is the easiest, and cheapest performance enhancements you can make without tearing into the engine. Big cams require higher compression to function properly, plus larger valves/better heads will increase that even more. But...start with the basics(intake/carb/headers/exhaust), and then you can build on that foundation later, as time & $$$$ allow. A good electronic ignition will help, too, but you may not be able to "feel" the increase in performance....

Go to a  3.73 rear gear.

|UPDATED|2/20/2014 11:24:40 PM (AZT)|/UPDATED|

You can get a set of Edelbrock RPM aluminum heads for less than the intake/carb/free flowing exhaust. Bigger valves, stainless seats, better flow AND port velocity plus....bonus, more compression with the closed chambers.....just sayin. Yes, its a bigger tear down but man, your on your way to a 450 HP if you wanna plug in the other matching bolt ons. 

Head swap would be one of ways to go. On dad's 76 it was a stock engine(180 hp) that  had been rebuilt stock which was probably for the best as i was just starting to drive and probably gotten into trouble if it had a little more ponies..... but that aside, i did go to a swap meet and found a set of heads, 1966 double hump small valve heads.  picked them up fairly cheap, had the local shop redo the valves and guides, which  actually costed more than the heads did... but the main thing i would suggest is that if you do 'shop' around for a set of older heads, do make sure(MAKE SURE) it has the facing and bolt taps for accessory mountings... the ones i got did not, a veeeerrrryyyyy discouraging detail i overlooked... but i was a little kniave then, didn't turn a wrench to often back then, but live and learn... long story short, the heads did add about 1500 more rpms to the redline area, and could definatly feel a bit more 'umph' under the hood.... that was with a 308 gear, later replaced with a 370 which did push you back in the seat a little more....