I guess it would depend on the cartridge you plan on using. Some people feel it doesn't hurt to have the base of a cast bullet protrude into the powder area and others feel it is a definite no-no. Personally, I'm one of the latter.
My reasoning is as follows. If the bullet is plain based, the flame of the burning powder may damage the base of the bullet. Even if it is only ever so slightly damaged, I feel it will affect accuracy. Second, if it protrudes far enough, one of the lube ring can and probably will affect the powder charge. If the bullet is gas checked, that check can come off. If it hits the neck in the right way upon firing, it could cause a pressure spike. I used to own a 6.5x54 Mannlicher that I shot cast bullets in. The bullet was quite long,was gas checked and it did protrude into the powder area. Upon firing, one load showed extremely high pressure, the primer pocket was quite enlarged, and the bolt very hard to open. Now there was enough powder in the load that a double charge was impossible. My thoughts were that the gas check had fallen off and dropped into the powder. When I fired the gun, the check must have been placed just right so as to have blocked the expanding gases for just enough time to kick the pressure well above what was normal. Having fired hundreds of that particular load over the years, that seems to be the only explanation.
Don't know if this was of any help, but those are my thoughts on the subject.
Paul B.

glichti,
I too don't like cast boolits protruding into the powder, though I don't have Paul's experience, there is the chance of that gas check falling off. Not everyone of my rounds is perfect.
Be aware of the various tricks you can do to the action on the Marlin 336/1895 to increase COAL, .100" over 'standard' is fairly simple, much beyond that and receiver and ejector mods start getting a lil tricky, 2.7" is possible, that extra fifty thou or so gets harder and harder to get. And then I would suggest you go for a 'longish' neck on your wildcats and bear in mind the practical limitations of circa 2400fps with cast boolits.
Faster is possible and has been done, but boolit shootin' is a bit different to the world of high speed, mach 2+, jacketed.
Just my $.02.
R*2