I think you need to look at the power/ torque characteristicts of the engine and the use/ speeds the car will be used for, close ratio boxes often have a high 1st, so may be slower off the line, an engine with a very wide torque/ power curve may be quicker with the std ratio box (once the time lost changing gears/ lag etc is factored in)

ideally you want to make charts with the speed/ revs in each gear/ on upshift etc to see the difference

Having said that, on balance you are probably better off with the close ratio box for hilcliming as a road box probably has poorly chosen ratios for hilclimb use

if the car is to be used purely for hilclimb use it sounds like you could lower the final drive a bit more so its flat out in top or 4th etc on the longest straight

have you any data from any runs?