might be the Maxrad MLB2700 27-31mhz will it still be good for low band?
Most antennas come with a cutting chart allowing the antenna to be cut to length to match peak performance at the frequency you desire. The 2700 is designed to be cut for wavelengths between 27 and 31 MHz so the cutting chart that comes with it only covers those 4 MHz. You would be better off purchasing the Maxrad MLB4000 which comes out of the box at a length that provides peak performance for 40 MHz. The cutting chart allows for a length providing peak performance up to 47 MHz.
If I had room for another radio in my vehicle and space on the roof I would install the 4000 cut it to 42 MHz. I would then use this antenna and the radio for low band only. Since the CHP is only using low band for their primary communications with narrowbanding and trunking not being factors an older radio you may have or could buy cheaply could be dedicated for this use. I would also install a newer model scanner, something I already have (PSR-600) allowing me to listen to all the other agencies, but also capable of receiving the CHP 700 MHz handheld frequencies.
I have Larsen scanner antennas mounted on my vehicles that work very well for 136-900 MHz, at least as well as one antenna can given the wide range of wavelength involved. My Forest Service truck had two Larsen WBQ-150 antennas installed on it. One for a Midland VHF High transceiver and the other for a BC-760 scanner.The WBQ-150 is designed for agencies that communicate over the entire VHF High Band, from 136-174 Mhz, using one length. I traveled all over the state to fires and other assignments and found that this antenna performed better on the VHF High, UHF and 800 MHz bands better, as a whole, than any other antenna I've ever used. It is only 18" high so getting in and out of garages and parking structures is never a problem. This is the antenna I initially installed on my personal vehicles. When Larsen came out with their scanner antenna I started using one and found it to perform a little better than the WBQ. It took about 45 seconds per vehicle to make the switch as both antennas use a NMO mount. I highly recommend the Larsen scanner antenna for anyone wanting good performance on the upper land mobile bands. Unfortunately, its performance on VHF Low is not that great, but it is better than other multiband antennas I've used.
Expecting one antenna to cover all bands at peak performance is similar to thinking we can have one animal that gives us milk like a cow; the nimbleness, speed, companionship and intelligence of a horse; and the ability of a mule to carry heavy loads. All of that and the ability to travel quickly and carry heavy loads over snow like a snowmobile. All of this without having a stupid slow cow, a ornery mule and a smelly, cantankerous, noisy and difficult to maintain snowmobile that gets stuck in soft snow before you can say "oh crap."
I don't drive that much as I live in a small town so it isn't worth the effort for me to install a second scanner and antenna just to maximize CHP reception. If I did I would seriously consider having a scanner just for the CHP.
