I'd consider sleeving the chamber and the throat. Done as far in as the chambering reamer will cut a new throat for you so the new chamber and throat flows nicely into the old bore. You get a new chamber and as much of a new throat as possible to get rid of the old burned up one.
Done right and with a tight metal to metal fit joint up front, it'll stand up just fine with any 30-30 loads I'd want to put thru a skimpy bbl'd drilling of that age.
Sleeving just the chamber or the chamber and throat of the bbl was not an uncommon repair on single and double rifles in low pressure rounds.
Some were done better than others of course.
You could even do the new chambering in 32-40WCF w/a 30cal pilot on the reamer. Then size the 32-40 brass FL but do not expand them. They then hold .308d bullets just fine.
32-40 pressures are quite a bit lower than 30-30 IIRC.
JMO and thoughts
