I’m going to wade into this thread because of your utter gall in mentioning LBJ. Regardless of whatever budgets the man may have run at the time, he oversaw the enactment of Medicare and Medicaid, which represent an ever-ballooning non-discretionary portion of the U.S. budget, currently above 20%.[1] Mandatory entitlement spending, which has been demographically broken for decades and politically untouchable for just as long, is the heart, brain, and lung cancer in the diseased body that is the U.S.'s finances.
I don’t disagree with your main point, however, which is that we cannot inherently trust Republicans simply because they like to portray themselves as fiscally conservative. Reagan jacked up the deficit tremendously. GWB was the biggest fiscal whore in U.S. history until Obama came along and somehow managed to make GWB’s dangerously unprincipled spending look good by comparison.
[1]see, e.g., 2010 United States federal budget - Wikipedia and Great Society - Wikipedia