Twud, You might consider buying (or having the guy who is building your rifle do it) a great quality case... a Pelican, and send it to the rifle builder to cut the foam for you. The pelican is expensive ($160-$250), and all that shipping (from the case dealer to the rifle guy, and then back to you) could get pricey, but when your rifle is shipped to you, it will arrive at your door or ffl guy in perfect condition as these cases are absolutely TOUGH!!!
You can though, do it yourself, and do so quite nicely if you DON'T do it the way I did my first one... I used a super-sharp knife (really, it was super sharp)... and butchered the hell out of it. The solution is pretty easy, and relatively cheap too. You use an electric carving knife (about $15 in housewares at walmart). Goes through the foam like butter.
First, I REALLY like the Pelican line of cases. My rifle is a 26"barreled Rem 700 varmint with a bigass Leupold on it. My case is the model 1750. It'll hold a 50" rifle. Actually, I think it's a double rifle case, but to me, 2 rifles with scopes would be pretty snug. It's a big case, weighs 22 lbs empty, has wheels on one end and a handle on the opposite end (like rolling luggage), as well as a handle in the normal carrying position. I reccomend the 3 piece, non-egg-crate foam lining. Each of the 3 pieces is about 1 1/2" thick. After I cut out the middle piece to fit my rifle and scope, I bought a can of Spray Foam Adhesive (available at a fabric store or hobby store), and glued the top piece to the roof of the case, the bottom piece to the floor, and then the middle piece to the floor piece. My rifle-fit is quite snug, but I can pull the rifle out without the foam coming out with it. Just be sure that you've adjusted your scope for proper eye relief, and have your bipod attached (if any) before you cut out the middle piece of foam. Also, don't glue the middle piece in place before cutting it out.
I really can't reccomend the Pelican highly enough. I figure that between my rifle, scope, and additional NV scope, I have right at $2000 invested. I'm sure as hell not putting them in a $20 naughahide (sp?) walleyworld case. If you're interested, email me, and I'll see about emailing you some web-cam pics. Sorry, I don't own a digital camera.
Robb