I would thing you could get a reputable gunsmith to do a rechamber in the $75 - $100 (+ shipping both ways) range. You will have to call around to find one that has a 30-40 reamer then find out how much they will charge. If you can not find a gunsmith with a reamer already, the reamer rental would be extra. If you want the ejector modified that expense would be in addition to the reaming and shipping charges. Personally, I would not do a 30-30 to 30-40 by hand, just too much metal removal and chance of doing it off center.
I have also rented from 4D. I did a 357 to 357 Max. Only the one reamer was needed and I had 10 days to get set up and ream the barrel, which took all of 15 minutes including setting up the vice. I can't remember the exact cost but I think it was under $40 including the shipping. I placed the order on line and got a phone call about 1 1/2 hours later to make sure I was going to get what I wanted.
I was thinking about hand reaming a short chambered 221 Fire Ball to 222 Remington for a 700 Remington BDL a while back. I was strongly advised against it by several people on this site in the gunsmith section. There is just too much metal to be removed, with a great chance of reaming the chamber out of round. It is difficult to keep the reamer centered (with out reaming the sides even a little) for the entire depth of about .3" I had to ream the shoulder. I ended up renting a reamer to make it a full depth 221 FB. I ended up hand reaming about .011" or .012". It turned out well. I have a 22 Hornet SL barrel that I have been thinking about getting reamed to 22 K Hornet and will more than likely sent it out to have done if I make up my mind to do it.
JFEI - Never, ever ream a chamber with a hand drill (powered or other wise); I do not care how short you are going to ream it. Do not use a drill press for reaming a chamber, unless you know there is minimal quill run out and you can get it set up perfectly straight and centered with the quill and bore. It would act as a vertical lathe. I have a drill press, but do not have the measuring equipment to ensure all the above measurements can be done precisely. It is much more difficult to do than you might think. Once you ream a chamber out of round, off center or not perfectly straight with the bore, even a little; the barrel will be a tomato stake. It is a chance I do not want to risk.