Recommendationx

What is the best 7mm Remington magazine load for a 170 grain bullet ? Thx.

Depends on the rifle and the powder you intend to use.

If you use the IMR 4064, you can only push it to a max of 2800 FPS.

you didn't specify 7mm rem mag...7mm win short mag, 7mm weatherby mag, 7mm Rem short ultra mag, they are all .284's.
but if we are talking 7mm rem mag......

I don't recall loading any 170's. I do recall loading 175's 162's, 154's, 139's, 120's, 100's.
What load works best depends on a lot of things like...
how persnickity your barrel is to different powders and loads, bullets, cases, primers, seating depth etc.
Then...
what ya huntin'? Thick skinned heavy game I'd guess if you are searching for something in the heavier bullets offered for .284's
my notes say I used to get a case of the happy feet with....
Hornady's 162 gr boattail spitzers for muleys and elk
win case
fed 215 LR primer
IMR 4350 @ 56.3 grains
COL 3.285
I like my bullets to fly a little slower than max loads....allows bullet to expand at a consistent rate resulting in better and bigger wound channel
but what works in my gun...may not work in yours
good luck