I don't shoot black so have no experience but recall reading a thread either here or on Beartooth that indicated some rifles needed a compressed load to shoot decently. Might do a search on both sites.
I have had flat miserable experiences trying to push plain base bullets past 1200 fps with smokeless.
If those bullets have a nice square base, you might get a 5/16" arch punch and start experimenting. Some folks have reported good results with wads under the base of the bullet. I've been meaning to try that with using an old offset printing blanket for wad material.
Ezirider, for what you are attempting, I'd look up 30wcf, aka, Slim Iorg at beartoothbullets dot com. He also posts on the cast boolits dot com board. He and his father have done more experimenting with the 30-30 then most humans can conceive and regularly shoots long range matches in the western Pa area. A gas check is a requisite, almost. He has load data with many results posted on those boards over the last 2yrs. Use the search feature on those sites. The Meisters are plinking bullets at best. Good Luck.
Unique is pretty much the go-to powder for light cast bullet loads. It's bulky, easy to ignite, and predictable. It also generates considerable pressure for the velocity it gives so you probably don't want to increase that eight grain charge. The gun will take a far heavier charge, but your bullets would have to be extremely hard to give any kind of accuracy. You might even want to decrease it a mite. Could be just me, but I try to avoid barely supersonic loads.
If you want higher velocities, read chapter ten in the Lee Manual. That contains some very useful theory and some excellent load tables for the .30-30.