You need to change your partition sizes. At the very least need to increase /system
And if you want to install a DataMedia (DM) ROM, you need to make additional adjustments.
Right now there are three (or four) KitKat (4.4.2) ROM's for the TouchPad (tenderloin) to choose from:
CM11 - 3.0 kernel (Milaq) - DM
CM11 - 3.4 kernel (invisiblek) - DM
Evervolv - AOSP - 3.4 kernel (flintman) - (two version:- one DM and one not)
If you want to install KitKat on your TouchPad will need to do some reading. Keep in mind all these KK 3.x kernel based ROMs are in development (experimental and/or for testing). Each has its own pros and cons, and various TouchPad features are not yet working, features you might have observed working in previous JB 2.6 kernel ROMs.
If you want to stay with JB, until KK is better baked for the TouchPad you may want to try out the new JB 3.x kernel ROM just released from jcscullins (01-25-14). It is NOT a DM ROM, whereas Milaq's CM10.2 (JB) is a DM ROM.
1. For each ROM you are interested in thoroughly read the OP. And suggest reading, at the minimum the last five pages of each thread.
2. Then visit [ROM GUIDE] How to Update/Install Android 4.2, 4.3 and 4.4 Builds on the HP TouchPad
3. Be sure to read the info on how to update your partition for DM support. If you decide to go with a DM ROM, I would suggest using Tailor to change your partitions since you have Tailor installed on your device already.
4. Backup your device before proceeding. Generate a nandroid backup in your recovery as well as back up your app/data with Titanium Backup
5. A "full wipe" in your recovery (factory reset, including clearing caches, formatting /system) is generally recommended when doing major upgrades (not just a nightly flash of the same ROM).
Once you have chosen a ROM to install, and have downloaded the zips for both the matching ROM and Recovery zips (note each ROM has it's own specific recovery version matched to the ROM), then you should be ready to upgrade.
If you have questions before upgrading post your SPECIFIC questions/issues, identifying the ROM version you are coming from and going to.