red line

+1 with what A/J has said.

You need a fairly deep set of gears and a fairly high stall converter to get the slant moving out of the hole. It's best to get a converter from a company like Edge or PTC to where you can specify to them that the converter will be for a 6 cylinder engine. Buying an off shelf converter for a 904 v8 application will leave you disappointed because you won't get anywhere near it's rated stall with a 6. I know that Edge will build it specifically to your combination.