Need Gears

[Schiada76]

Anyone have ten degree 18's they will trade for 12's?
Also have a question.
I'm running a 500ci BBC with an 871 and a chiller, 13% over about 12 #'s boost in a 19' with a slight vee.
Going to injection and was pulling 6700 to 7000 rpm with the carbs.
What changes will I get with taller gears, rpm and speed, and should I go with 15's or 18's?

[Schiada76]

So the rule of thumb would be to gear to acheive your RPM goal?
The motor is going back together with a little different configuration, roller cam and the injection so should I run the 12's for a bench mark then try a gear change or know that I won't be losing HP and go ahead with the change now? :confused: