First, I want to acknowledge my respect for you and your desire to honor your father. You sound like the kind of fine man and good son that makes for a good friend too
You are definitely on the right track. I would suggest that the 6.5 mm bullets are far superior for this application due to their high BC for the light weight ( 130/140 ). The BC of a 6.5 mm 140 VLD is MUCH higher than the BC of a 7mm 140 VLD. The sectional density is also much higher, etc.
Any of the following would meet your criteria quite well:
260 REM,
6.5 Creedmoore
6.5x55 SE
6.5x47 Lapua
Lapua offers super fine brass and loaded ammo for 6.5x55 and 6.5x47.
The 6.5x47 Lapua running 130 VLDs is a sweet sounding rig. Super efficient, super long barrel life, very low recoil, great brass - PLUS IT'S COOL! Even old guys like COOL STUFF!
The 6.5 Creedmoore? Only one source of brass - not sure about it's staying power yet. It doesn't really do anything more that the other cartridges (except for 6.5x47L - case capacity, but in the field? not that big of a deal) but I like the cartridge design. If Lapua offered brass for it, this would be my choice, but alas...
Please update me on your final results - love this idea of yours.
-WindRunner