My experience has been that the Hayward pool valves are lower grade than the Hayward industrial valves.

Will this make a practical difference to you? Dunno. What's going to matter is whether you can operate the valve. Larger ball valves can be 'stiff'. That's why I suggested the S-80 nipple as the attachment point, so you will have a firm strong connection to stand the torque of handle operation.

One caution: AG filter "design flow" is bogus, and has been for years. Sand filter 'efficiency' at particle removal INCREASES as flow rates DECREASE. Inground pools are rated at 15 GPM per sft of sand filter area. Above ground pools are rated at 20 gpm. An 18" filter is rated at 26 GPM for an in-ground pool, but up to 35 for an above-ground pool. The lower rating on that filter is possibly that it has a shallower sand bed, which lowers the rating. Unfortunately, for good filtration you need to run at 12 gpm/sft, or 22 gpm.

Why the difference? Just because . . . of marketing needs. There's no science or engineering behind it; filtration requirements on AG pools are actually MORE demanding than on IG pools.

So, do what you like. But 58 gpm is more than TWICE the optimal flow through that filter. Low speed probably won't be enough to backwash, but on high, you'll likely lose sand every time. And if you ever turn it on 'high' when it's set to filter . . . you'll clean the sand right into the pool!