For those not in the know Rockfist was an RAF fighter and champion boxer who appeared in The Champion, a boys story paper from the Amalgamated Press (which ran from 28/01/22 to 19/03/55). The stories were written by 'Hal Wilton' (actually legendary British comics writer Frank S. Pepper - creator of Roy of the Rovers and Captain Condor).
There were 3 'tie-in' books published
Rockfist in the kingdom of the Khan
Rockfist at the North Pole
The jet-plane spy
Hunting the Hawk
Peril in the explosives factory
What's wrong with Rockfist?
The gold pirates
A shock for Rockfist
The land of skulls
The truth about the Tortillo affair
All of these were originally published in The Champion
The book is 135 pages long and the cover picture is from a painting by R. Simmons
Advertised but not appearing titles were
Rockfist King of the cannibals
Rockfist Rohan - Spy Hunter
All 3 novels are undated and normally cost £20-£30 in their dustwarppers.