With regards to the .270Win and his wishes to have a gun for longer shots I told him that a custom would be the way to go because he could have it built with heavier bullets in mind. Anyone have any experience shooting heavier bullets with a .270Win?
Never owned or built a .270, but no reason it wouldn't be capable of shooting heavies.
Potential "downside", is that bullet selection/availability in .277 is very limited. Nosler, Berger, Sierra all make heavy hunting bullets, but zero target bullets (Sierra does make the MK in lighter weights). Since it seems the application is strictly hunting, probably not a consideration.
The .270's "replacement" as it were, the short/fat .284 Winchester- will do anything the .270 is capable of, with an infinitely larger selection of 7mm boolits. Though it was designed with a short action in mind, running it in the long action would absolutely eliminate any issues seating out the heaviest of VLD's and still be within mag length constraints.
Keep in mind that the greater the demand for accuracy, the higher the cost as would be expected. Sako Finnlight II is less than half the cost of the Proof Research Summit mentioned above- but the accuracy "guaranteed" is double...
Good luck, always fun spending someone else's money