Factory high stall converter

I have used the stock 340 hi stall 727 converter behind 318, 340, 360, 383, 400 and 440s. The 440s flash stalled to about 27 ish. 318 to about 2350. The others to about 2500. I would say to talk to a converter company and give them all the info about your build. I bet they all come back at about a 3500 stall. The new converters are light years ahead of the old slush boxes. I’ll add that the new converters are way more efficient. U will surely be leaving power on the table with an old hi stall. There is nothing like a good converter to make your project come alive. Kim