There are lots of good actions and barrels out there that will do what you want. I normally recommend the Remington 700 (Short Or Long depending on the cartridge you chose) because of ts ability to be very accurate and the availability of Stocks, Triggers, scope mounts and any other accessory you want.
They are simple, abundantly available, and respond well to accurizing. There are other good actions
available but the 700 is my first choice.
Good Barrels are another item that comes down to choice but like everyone I have my favorites base on
quality, performance, velocity, longevity, consistency, ETC.
My preference in order is Lilja, Kriger, Hart and so on. Other people may/will have there preference in
a different order/brand, but this is just my opinion.
There are many fine calibers to choose from, and I suggest you start with the game to be hunted, the max distance you will be shooting, if you reload and any other information you can give us. With this
information this site should be able to guide you through the selection process for your build.
If this is your first custom build feel free to ask questions.
Good luck
J E CUSTOM