If you are determined to build your own custom rifle around a Remington 700 you are basically going down the tube gun path. Just google "tube gun".
Gary Eliseo makes a kit that you can attach the action and barrel of your choice and four around $2,500 you come out with a custom tube gun.
"Socialized Medicine is the Keystone to the Arch of the Socialist State.” -Vladimir Lenin
"I predict future happiness for Americans if they can prevent the government from wasting the labors of the people under the pretense of taking care of them." - Thomas Jefferson (An early warning to Obama care)