Seeking long-to-peak (6-8 hours) starter and flour query

Toast

Hi, my starter peaks in 2-4 hours and teacher Teresa Greenway told me to get the longer fermentation I want, I need a longer starter. I can trade or buy. I can also offer my vigorous and fast starter if anyone wants it. 

Secondly, has anyone here found King Arthur flour weaker in gluten development than other flours, whether AP or bread? And has anyone tried Champlain Valley Milling for white and whole grains? These are the flours we have locally. I am thinking of ordering Heartland Mills to try. 

Thanks..

Depending on how often it's fed, how much starter to fresh flour and how warm it is will affect your starter.

What's' your maintenance schedule?

... can also be achieved variously through the judicious use of salt and/or refrigeration, both of which retard the process.  Will these not meet your objective?