Which engine oil for a 1968 Sportomatic?

Can anyone recommend the best engine oil for a 1968 Sportomatic?

I think the engine oil also goes through the torque convertor.

Because it's hot down here I use Brad Penn 30W, but any good oil is fine... multi grade like 5 or 10-30W for cooler climes or winter. They need 20W or lower below freezing.

And yes, you're filling the torque converter too so it'll take 10 quarts total.

Thanks! Am a Sportomatic newbie so still learning