Well I was just about to post this on your other thread but saw this one.
Going with either cast or jacketed you should look into the powder coating thing if your needing to bump the size up only that little bit. Cast would probably be easier, but hey, they are powder coating anything that resembles a bullet now, some have even done some of the steel cases.
I can't speak but of only what I have done personally, but a couple of weekend back I ran some 175 and 180gr PC'ed cast out of my .308 loaded over 38grs of H-4895. I didn't have the chrono set up so can't give velocities but they shot VERY well and didn't seem even close to reduced loads I have shot in the past.
For testing purposes, I would lean hard on the
Lee 2C 329-205
If that works out through your initial testing I would go with a good mold form Accurate Molds listed
here.
There are a couple of lighter ones listed on the previous page as well. Tom makes an awesome mold and will have it to you in only a week or two, which isn't bad for a custom mold.
I would even give some of the closer diameter jacketed a dose or two of powder and see how they work. Using one of the Lee push through sizers in .323" it would only take a little bit to polish it out to your exact needs using a wooden dowel and some fine wet dry. You could then size either cast or powder coated jacketed to the proper diameter. Either way, it's not like your going to have to spend a couple hundred for something exotic just to see. Going Lee will get you there under $75, and I bet if you asked, there is probably someone here (hint,hint, see above^^) or over on Castboolits who would send you a few to try out before hand.
I have to say that is a VERY nice rifle and if it were mine I would be itching to get it out somehow some way and make it go bang if for no other reason because it deserves it.