Re: gALAXY 500>> thats 'Galaxie'... : )
When I was 19, I could barely afford the gas for my car, but most bang for the buck I got was a boneyard 4v iron intake/with used carb. rebuilt carb, back then cost me about $75. Big power difference. Next got headers/duals- cost 150, sounded great, but not really that much noticeable power(sure if you wound it up, but in everyday driving, no diff).
If I had to do it all over again, I'd have saved a bit more $ up, done 'towing grind' cam/lifters/chain/iron4v(spreadbore for better mileage than 2v) all at once.
Next step would be duals on iron manifolds- these cars are so heavy, the few pounds youll save with alum intake and headers wont amount to much percentage wise, and I hopefully will never, EVER buy another set of headers for a street car...friggin gaskets blow regularly, changing plugs becomes contortionist act, underhood heat soars, starter life goes downhill...you can wrap them in insulation, but foul weather/moisture= rustout...never again for me.
Build motor for low/midrange, and in my opinion its a lot more 'powerful feeling' in normal everyday driving, and you might even SAVE money on gasoline. I threw away every hard earned penny I made back then for big cams/carbs/exhaust, ended up tired of the lousy idle,horriffic mileage, and tendency to get into trouble 'getting into the powerband'...then went backwards for a more powerful feeling motor, that would idle when cold, and not kill me in gas costs...just my opinion.
Confidence: that feeling you have just before you realize the mess you've gotten yourself into...