I still have my first custom build. I started from a barreled action with trigger. Stripped the trigger and barrel, trued up the bolt and receiver. Put on a new trigger and barrel, bedded it into McMillan stock, mounted glass, and went shooting. It is in its third stock -- all three are McMillans and its third scope -- all three were Leupold. It has the first trigger that I put in it (Arnold Jewell) and a new brake (Harrell). It is on its fourth barrel and I have another one coming. The gun has always been a 300 Win Mag, the first three barrels were tight neck, this one is a standard neck.
The big decision is receiver length. Everything else is adjustable. Suppose that you get a Remington long action. Suppose that it comes with a .532 bolt face. You can get a custom bolt from PT&G with a .473 bolt face - roughly $200. That fits 243, 6.5x55, 308, 30-06 and a whole bunch of other stuff. You can use your original .532 bolt or get a second PT&G bolt with a .532 bolt face. That fits all of the belted magnums. Want a new caliber? Buy a barrel and have it chambered and fitted. Want to play with stocks? Buy one, bed the receiver to it, cut the barrel channel, and try it out. If you use Badger or other rails, you can swap scopes between guns.
I have other Remington receivers. I have settled on McMillan A5 stocks, Badger bottom metal and detachable magazines, Jewell triggers, Harrell brakes, and badger rails and rings. They are modular.
I have more than one weapon in the same caliber. When I have a new .308 barrel fitted, I have the gunsmith fit the new chamber to the existing brass -- so they all can shoot the same ammo.
Except for the argument that I need the cash from this one to buy the next one, I don't understand why someone would sell a rifle. If the receiver is sound and of a usable type, everything else is adjustable or replaceable.
That is me and my approach, you will have other requirements. Just my thoughts on the issue.