In terms of simulators - the more they cost the more potential they have to be more accurate. Pipemax is very accurate but you really, really need to know what you're doing to get everything the program can give you, and the outputs can be dificult to read. It's not designed to be "easy". Even the best is still dependent on solid inputs like Sinatra said.
As for the basics - you don't need a simulation is you follow these guidelines:
1. Smaller head chambers, matched with a quench dished piston brought proud of the blueprint deck height will yield a great, pump gas friendly package around 10.25:1 static with the Felpro 1008 gasket.
2. Choose heads and cam together based on your needs. Take the cam's advertised lift on the intake side, subtract 30% for durations less than 240 degrees, and look at the flow numbers for that lift of your heads. Multiply that flow number by 2, and you have a good idea what the engine will make. Using what you've posted: 70% intake lift for the "704" cam is .350". At that lift, the 360-1s flow around 240 cfm in ported as delievered from Indy. So I'd put the horsepower in the 480-490 area based on the choices. I think you're pretty close to what you want.
