The cam you are running is milder than mine was, which was mild too. I consider anything under .5" lift to be mild. I had a stick shift though, so converter slippage was not an issue for me. You have to remember that part of the reason OEM's went to lock up converters was because of highway gears, tall tires and mileage issues.

I once ran a 360 powered Dart with 2.26 gears, tall tires and a non-lockup trans, which got worse mileage than the 413 powered 300 with 4.10 gears, because the converter was always slipping at legal speeds.

You may wish to do a bit of math and see what your highway RPM might be. I did one for you, at 60 mph, with 3.23 gears and a 28" tall tire you are looking at about 2300 rpm, this is no converter slippage. As long as your converter stall speed is below this you ought to be ok.

They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.