Sounds like an interesting project. You will probably want to do a chamber cast or hammer a soft lead slug into it to get the actual throat dimensions and location. It may change your mind about those long protruding round nose bullets in groove diameter, though you can, of course, cast a bore riding nose design bullet that fits.
NEI's catalog shows their #98 mold is a gas checked 245 grain, .330" bullet bore riding nose design of close to that shape, though it has a fairly wide flat meplat, which should be good for terminal ballistics. You'd have to call them to ask what the diameter of the nose actually is, though.
As to gas checks, if they were going to stick in a bore, I expect someone else would have had that happen by now. The reason they don't is the propellant gas pushes on the check, while the check is what then pushes the bullet. So, if the former isn't being pushed out of the tube, the latter isn't either. There are problems with the old style smooth-sided gas checks coming off after the bullet clears the muzzle and tumbling into chronographs or putting extra holes in close targets, but the crimp-on style won't.