what torque converter options are there for a '69 C6?

I never buy off the shelf converters. I go to the local converter builder/rebuilder and get one custom made for my application. Oops....you are in the Netherlands...this may not be an option for you, sorry. I think you should call B&M and ask because what the differences are in years of C6s. Contact TCI also as they might be able to help.

try these guys: Performance Automatic

they make your tc according to your engine strength and vehicle purpose. they aren't the cheapest but reliable and quality are never cheap