There's a few decent ones out there... I'm using Bamf Forever. All of the newer ROMs are Gingerbread so you will need to upgrade your radio as well. As for kernels I'm using Imo
You can use this guide for ROMs and Radio installs:
http://forums.androidcentral.com/th...-backup-restore-install-roms-thunderbolt.html
At the end of the guide is What's Available for ROMs/Kernels/Radios.
Heres my setup as an example:
Gingerbread 2.11.605.3 Radio:
[RADIO] HTC Thunderbolt Radios [PG05IMG.zip] (Updated: 20 Oct 2011) - xda-developers
Bamf Forever ROM:
[GB][2.11.605.5][Sense3.0]BAMF Forever 1.0.9!)
Imos lean test Kernel:
[Kernel] [GB Sense] leanKernel: minimalistic kernel (4.1.0GBtest, 10/21/11))
For the radios... you need to flash/install twice... one at a time.. one for CDMA and one for LTE. Just follow the How To ROM Guide and repeat the process for each radio. Make sure you remove the first CDMA radio off of the sd card before placing the second LTE radio on it.
For the Bamf ROM... version 1.0.9 is just a fix/patch (not a full ROM) so you would need to install 1.0.8 first which is the full ROM.
That's just an example of my setup.