If a "barge blitz" is used, surely those barges were not sent to the PRC overland, wouldn't the US send ships to begin to intercept (possibly "quarantine") them knowing something is up before too large an armada is built up in the PRC? An early version of the Cuba Missile Crisis perhaps. And, sure the PRC has a large number of people to conscript, but especially in the 1950s do they really have the armaments to go along with the people to lead a successful invasion of the RoC without affecting their commitments to the Korean War?
More questions- Could the PRC use an invasion of the RoC as a negotiating tactic... "USA, we will pull out of Korea in exchange for you giving a free hand to our invasion underway in Taiwan". Would the USA sacrifice Taiwan just for Korea? How would this affect Vietnam later on?
Bump - awesome questions.