Jack makes good products, the M77 Mount included. It’s not the most aesthetically pleasing and it sits a little taller than a D&T mount can be made, but it’s solid and holds firm. I like to use Ruger rings when I can, or Alaska Arms, but I use the Weigatinny if/when my optic won’t fit the integral base spacing.
Seekins rings can be purchased a bit cheaper by getting them as Vortex PMR rings. Same rings, still made by Seekins, just different logo. I like the Seekins/Vortex rings; very rigid, perfect alignment on a straight rail, and high contact, right out of the box. Burris XTR Zee rings can be a nice option for M77’s if you want to add some angle to your system and maximize your range capacity.