Hi there,
If you are seriously looking to make those sort of figures and be a daily drive, your best way of doing it is to turbo or super charge it. If you want to do it naturally aspirated and stock stroke, then you're are going to be spending some serious money not only building the engine itself, also it's upkeep, let alone the rest of driveline will need some serious upgrading as well. Once you've got that all done, then you've got to strengthen the vehicle (because that sort of power will just twist that thing apart) then you're looking at setting up suspension to get the power to the ground. Add all that up and you better have some very big bucks just to build it, let alone running costs, keep up with maintenance and so forth. It becomes very expensive for a car to play with, let alone trying to use as a daily street car. As for this BS about heads flowing whatever claimed numbers out of the box, that's exactly what it is BS. A guy I used to work for and who I use to do all my serious intake manifold and cylinder head work, just laughs at all these "claims" of out of the box numbers. As he says, it's not to hard to manipulate the bench to give what numbers sound good to sell a product. I've seen this myself on his bench, as his is calibrated to how it should properly be, he'll tell you, put his stuff on most guys benches and his will be around 20 cfm (lower) different. Top of the chart flow numbers is what sells these heads to everyday people, it's what they do and what they can achieve overall, that serious engine builders look for. If putting on a set of heads that claim 680 hp and you think that's what you'll make, then everyone would be doing it, because it'd be that simple. Well it's not, a lot of research and development of trial and error go into proving what works and what doesn't, such things you'll be looking at: Block, maybe standard bore, but a whole lot of work needs to go into it too make it hang together, Crank, to make a stock 351 crank handle that much power, be cheaper to buy a scat or eagle gear as a minimum, conrods, forget it stock rods will never handle that sort of power, again as a minimum scat or eagle gear, pistons, depends on what comp you're after but will be forged. Camshaft, solid roller, need to get a custom ground one and they want to know everything about the engine and driveline as well as the car it's going in. This is just the basic bottom end, you still have sump, oil pump, drive and pick up, timing set (probably the cheapest thing you'll buy) harmonic balancer, flywheel/flexplate, roller lifters, pushrods. Then you have the top end, cylinder heads, just bolting them on like this will not get this power, plus changing any incompatible parts, so buy them bare and use the components to suit your application, rockers, guide plates, studs, unless going shaft rockers, intake manifold, forget using that torker, high rise intake with a bit of massaging, carb, your 850 might be ok, but is going to need a lot of work done to it, probably cheaper to buy something else. Whole ignition set up, exhaust system, doubt very much your headers are capable of supporting an engine like this and no off the shelf set up is able to give an engine like this it's maximum power. You still got bolts, studs, gaskets and the rest of the under hood things to go, then on top of this you still got the driveline, because no standard toploader or nine inch diff are going to handle these outputs. As Luke stated before there are plenty of tuff street/strip Cleveland powered cars here in Australia. If your idea of a street car is doing around 50-60 M/hr on the highway, because of the revs with low gearing and swallowing a tank of gas in around 120 miles. Then on top of that always tuning, servicing and keeping up maintenance to help keep it from going bang, because engines like these are not a set and forget type of engine. If this is your idea of a daily driven vehicle then go for it.