[DavidNJ]

This would be a great time for Barry to chime in, but I think he is working hard on his EMC motor.

There are various things that could be the limiting factor. With hydraulic lifters, flat or roller, the valve train mass is probably what kicks in first. You can only use so stiff a spring, and those 3/8" stem big block valves are heavy. Going to a solid tappet allows more spring. And you could also use a 11/32nd or even 5/16" valve stem and/or titanium valves.

Next is the bottom end. All those cast Scat cranks and rods work great until 6500-7000. But by then you are swinging around a pretty heavy piston, pin, and rod. At this point you will need a lighter piston with a smaller pin and probably lighter, stronger rods. All this is available and there are 8000+rpm big blocks running around.

Next is getting it to breath. Now with a prepared tunnel port or SOHC, that shouldn't be a problem. With an Edelbrock or Blue Thunder, even KCR or ET prepared, it will be pretty marginal for an over 7000rpm 500cid engine. The best ports flow as well as stock LS7 427 head.

North of 7000, you are probably looking at a solid roller cam. And probably a longer duration that will be noticibly rough at idle and difficult with low speed operation. And since this thread started talking about a side-oiler, I'm assuming we are talking about cross bolted caps.

After doing that, where are you going to put the engine? I think their are 800+hp Galaxies, Fairlanes and maybe Mustangs running around. But to handle that much power you will need a prepared transmission, rear end, drive shaft, axles, and with a manual trans clutch.

I think there is a picture on this site of an 800hp Cobra with a cage (and a roof), but I don't know where. Don't remember if is is a high rev normally aspirated engine or if it has forced induction.