I've ran the Edelbrock Performer RPM heads on a 501 and am still very pleased with them! In a 2600 pound tube chassis car with a 'glide and a custom grind Comp cam (solid roller) it does 500 torque to the wheels! However, this is at 12.5:1 CR and running E-85 fuel. Couldn't do that CR with pump gas, about 9.5 or 10.0:1 CR would be tops, and compression is horsepower! As for the gas mileage, it would get some and it wouldn't be good, maybe 8 or 9 mpg when you build a big block to get to the 600 level. The rest of our 501 is a port matched single plane intake, 1050 Dominator carb, MSD pro Billet distributor and MSD 7 box, so it's good power, but spendy to put together. The best news on the 501 is that it's ready to start it's 5th season in a bracket car, only problem with the engine is that it likes to break oil pumps! Other then that, only a couple sets of valve springs have been the extent of annual maintenance!

If you're doing this for a street car, 450 hp is a lot more doable and is still more then enough power to blow the tires off on anything but the cleanest streets! Less power in a light (under 3,000 lbs) car with good gears (3.70's are nice on the street), good suspension, and good tires will be a much more driveable car that has plenty of power that can be acutally hooked up on the street with street tires!!! There's a lot more to this go fast on the street stuff then just a big hp number, takes a complete "package" to have a car that works good in is still in the driveable level on power.... Many newbs start with a big #'s engine, then can't do anything with it cuz the rest of the car just isn't up to the task of applying the power!!!!