Depending on the cam specs(and low speed engine vacuum) a converter that’s too tight will lead to poor in-gear idle and very low speed characteristics, and possibly be keeping the motor operating in an area of the power band where it’s not quite “up on the cam” yet....... during normal “in town” driving situations.

Even my Honda Civic and 2500 Silverado 6.0 have converters loose enough where the engine is rarely below 2200 rpm driving around in town........ and those are 100% stock engines with tiny cams.

Frankly, with MW sized ports, I’d expect the motor to be happier with a little extra rpm(and the accompanying increased port velocity) that you’d get with a slightly loose converter while being driven around town.

Again, for me........ most of the deciding factors would be based on the cam specs and engine vacuum.