Hello all - again

I am proposing to stick inlet rocker shaft into lathe and drill out and tap solid end plugs 1/4 or 6m so that I can clean out any loose solid carbon .

Before I do anything that I might regret, is there any reason I shouldn't , as in new plugs available, or turn up new interference fit plugs, or anything else?? New plugs (plugs) not mentioned in PM

Cheers

Rick F