I would research and interview some gunsmiths first. Establish a comfortable relationship with someone who is competent, especially one who has built a rifle like you are want to build.
Some smiths order parts and some want you to order them. If the latter is the case, then you will need to familiarize your self with how to order or buy a barrel, stock and action, as well as what twist rates will accommodate the bullet(s) you intend to shoot. You will also need to learn the ins and outs as to how to order parts. At first ordering a stock can seem intimidating.
I always start with the weight and type of bullet I want to shoot and build a rifle around that. Even though I've built a few, I still run my idea by my gunsmith to make sure what I have in mind will or wont work.
Having said that, the 6.5 Lapua is an easy one to build for. Can be feed with detach mag or internal mag.
I would have an ideal weight of rifle in mind too before I started. Your smith may also be able to help with that area too. Also, there are several on this site who "have been down the road" and are a wealth of information.
The rifle and round you are wanting to build is not that difficult and easy to obtain.
Good luck