Best way to slow car down?

Well guys dad took the car out this past weekend and did some testing, Friday night the car ran a best of 6.27 but the car had some leaks and it seemed to also have a vacuum leak because it would idle at 2000 and would not go below that at the time. I was not able to make it to the track because my sister-in-law was in town for midtour leave so wanted to see her, but Saturday dad unloaded her off the trailer she ran a 6.14 the RPM shift chip went out on the next round so dad had to shift it himself and it went something like a 6.22, he tried to fix the rpm selector switch but it still would not work so he had to shift the car himself again on the 3rd pass and she ran a 6.17, the only change to the car was we put a new crank in her after ruining the old one buttoned her back up and put a Jomar Spacer on the car, and we also went to a bigger slick cannot remember the size now though. We will switch the 4.10's out for a set of 4.30's we have already set-up and maybe play with the jetting and timing some and hope that gets her to 6.00, also will try to put a carb pan on the car if we can get a good design that we can make, right now there is nothing there under the hood. We had one made that came up in front of the carb up to the hood, and than also bent up on the sides at a angle to go with the 6 inch cowl but after putting the spacer on it raised the carb up to much for us to use it as it was, so back to the drawing board. Thanks guys for all the help, hopefully we can get her in the 5.90's 6 flat range for the next heads-up races.

Thanks,
Doug

as you can see with the pic I am not sure how much help just a flat pan would do around the carb.

Slow it down??? Maybe let me build the next engine for it...yea that would work!