The .270 offers several advantages:
1. Optics for much better precision shooting, which I would want vs. bear
2. Penetration, especially on shots through tough bone and tissue
3. Significantly more energy, especially at 100+ yards
4. Much better selection of premium bullets, which again I would want vs. bear
Nothing wrong with the .30-30, will do the job with the right bullet within the limited range given. Just that the .270 would outperform the .30-30 in all categories except possibly rapid follow-up shots and overall rifle bulk and weight, two rather minor issues unless you are stalking on foot within short range.
Don't want to recommend specific loads, but something in the high-end range of energy for both would probably be best. I would choose premium bullets (partition, A-frame, core-lokt, bonded, etc.) in heavy-for-caliber weights.
May you soon enjoy a late-night snack by the light of your bear grease candle!