from what i have seen and read, long rod motors tend to not run very well at low rpms. yes they do make great power but they are a pita to drive on the street because the dwell time of the piston is just too long at lower rpms.
Yea, my buddies car has a long rod 393, and it put down 425 rwhp in an 86 LX, traps 125 mph all day long. I drove it and could not beleive the difference in the torque in his 351 motor and my 302 based motor. his car Feels faster than mine, i guess due to the extra torque... he has not complained much about driving it around at low rpms.. but then again, he does not drive it around too much....
I would suggest getting a program called desktop dyno. It was put together by an Irish engineer and its is quite acurate. The biggest help will be that you can change the cam specs and see the results instantly. I believe its good to 5%+- actuall numbers. We use it in our engineering program and its pretty slick. We built an engine setup similar to what you were thinking on the program and by messing with it for an hour or so we got what we wanted. You can get the basic program for around $50-100. Just a thought