First Build.....360

Other things for a power est. would be;

Cam. Have specs on hand. Comp cams, lunati or hugesengines list the cams durations as advertised, @ .050 and there timing events and the cams lift. Rocker ratio. http://www.hughesengines.com/Index/index.php

Actual ratio
head port flow numbers. If you do not have them, state what head, letter or last 3 numbers of the heads casting numbers, like "308" or "576" and what valves are in them. (Size)

Exhaust size/Pipe diameter.