The 300 has 6 main caps compared to 4 making it a contender to hit 8,000+ rpm's. There was an article in HotRod recently where a guy dropped one in a Maverick, attached a blower and hit 8's in the 1/4. The limit factor is the heads but you can either add a 240ci head and bump the compression from stock 8:1 +/- to around 9.5:1 and gain some ponies. Or shave a 300 head to match what cam you want to run. Stock intake manifolds suck. And if you can score an Industrial 300, you score a forged crank. I've heard a 390 holley is about as much carb you want to put on one? The Offenhouser C-series intakes are comparable to a Clifford.
That about drains all of my 300 knowledge...