'76 304 HP Help

I would try to find a cheap 360 and rebuild that to replace the 304 if you want more power. You could continue to enjoy the car while getting a more powerful engine rebuilt. Dollar for dollar it is actually a little cheaper to rebuild a 360 than it is to rebuild a 304. 360's could be bought pretty cheap.

However if you are set on hopping up the 304 yea, a performance valve grind, aftermarket intake and cam will help it out a lot.

$ for $ the 360 is hands down the higher HP motor and the $ amount is almost exactly the same for either. 

The place where a 304 will make sense is if you're repowering an older vehicle that came from the factory with a 90-100 gross HP six cylinder engine. going from a gross 90 HP to a gross 150 HP would be a 67% improvement there. There's no way to do that in your Matador unless you swap in a 360, and even then, unless you take a decent swing at it, the results won't be quite as dramatic as you're probably hoping. The 360 CAN be built more inexpensively than a 304, but after figuring in the cost of acquiring a decent core [$750 or so in my area], your $$ per HP gained is still going to be substantial.

What I'm trying to say is, building any AMC engine is never gonna be as cheap as building a SBC. Never was. But even then, the days of the $75 junkyard 283 and a $250 performance rebuild are long gone, and we'll never see those days again.

But if your heart's set on building that 304, do see about stepping up to at least 1.84/1.5 Chevy valves, and a decent TORQUE cam, if you're building it for the street. If it'll never be more than a sassy grocery-getter, consider an overdrive automatic swap and a ring and pinion change. And if you're going into the rear end, then the Dr. Diff 1-piece axles should be another upgrade. [See how quickly the COSTS are accelerating here?]