Honestly i think some right wingers may be easier to "convert" than many liberals. It all depends on how deeply entrenched their views are and how big a role racism plays in them. Because as you pointed out, there are already points of agreement which are not shared with liberals about the unreliability of mainstream media, the recognition that the system is not working, and so on which can be built upon.
The main obstacle is to get them to recognize that bigotry and racism are a false consciousness, that these are deliberate distractions by the ruling class meant to divide and impede the formation of actual class consciousness through the use of scapegoats and prejudice. This also goes hand in hand with rejecting notions that some people are inherently more deserving than others, which is an idea used to justify the exploitative hierarchies created by capitalism.
In general i would say it's not so much whether someone is a liberal or a conservative that determines how easy it is "convert" them, it's how invested they are into their current ideology. The more they think that they "know" about the world and the more their worldview is "calcified", so to speak, the harder of a time you will have in convincing them to be intellectually open and willing to rethink their beliefs.