Dutch,
I don't know what velocity levels you're looking for in the way of velocity. I've got a couple of proven loads, the best of which is this one: It's a full power 2300+ fps load.
BTB .310"-160g WLNGC/33.0g H335/WLRP/Rem Brass
For a plinking, fun load with the same 160g WLNGC bullet loaded over 11 grains of Red Dot any primer and any brass. It will deliver about 1600 fps and is economical to boot.
Sizing diameter is crucial in any application, but especially for your .30-30. Slugging the throat and bore is the only sure way to tell, but most guns like yours thrive on .310" diameter bullets.
Hope this helps!
God Bless,
Marshall