Stock convertors are around 1600 RPM. That cam should be able to idle down nicely. What does it idle at?
I see no reason to use a 2200 convertor. That cam makes plenty of TQ. I'd go with the 1800 in a heartbeat. Maybe even consider a 1600-1650 convertor. Your vehicle is hevy and will also cause a convertor to slip more as the rpm's are less than it's rated 2200. Sounds slippery to me.
