I enjoy putting virtual dyno engine combinations together, particularly for street-driver applications where a fellow needs good torque right off idle and good power to 5,500. I was able to rescue my desktop HP from my ex-wife's house, so I have the Dyno-Sim with Pro Tools software again.

This is an excellent way to get in the ballpark with a build before you ever buy the first piece. I'm not saying that it will rival a hard dynomometer, but the stuff I publish has shown to be within about 2% of the figures obtained from a hard dyno pull. I use the head manufacturers flow numbers, but discount them by 5% to 10%, depending on how much I think they're fudging on their numbers.

Here is the basic information that I will need to run a virtual pull....

Bore
Stroke
Rod Length
Cylinder head flow, intake and exhaust 0.100" through 0.700" or whatever the mfg gives for range. The flow of thousands of heads is given on this site....
Stan Weiss' - Cylinder Head Flow Data at 28 Inches of Water -- DFW / FLW Flow Files for use with Engine Simulation Software
Intake valve diameter
Exhaust valve diameter

Static compression ratio. To figure SCR, you will need 5 values:
1. cylinder volume in cc's
2. chamber volume in cc's
3. piston deck height volume in cc's
4. piston crown dish volume or pop-up volume in cc's
5. head gasket volume in cc's
I'll can figure the volumes for you is you'll supply me with some measurements.

CFM, type of induction (2-bbl, 4-bbl, TBI, TPI)
Intake manifold type, mfg (single 4-bbl, two 4-bbl, one 2-bbl, three 2-bbl, individual runner Weber, mechanical fuel injection, low-rise, high-rise, tunnel ram, dual-plane, single-plane, part number if you have it. Be advised that after doing scores of these sims, I have determined that the Edelbrock RPM, Holley 300-36 or Weiand 8016 (out of production but available used) will work best for a spirited SBC street motor. These manifolds are knock-off copies of the original Winters Foundry aluminum Chevy 302 Z-28 manifold and will work well on a 355 and really well on a 383 or 406.
Exhaust system (be specific, primary tube size if long-tube headers).
Camshaft
Part number, grind number.
Type (flat, roller, solid, hydraulic).
Intake valve lift, exhaust valve lift.
Timing info and at what tappet lift the info is valid, i.e. 0.006", 0.050", etc.