". . .Remove the entire core where the line runs through the blocks. Leave the core and remove the jacket where the line runs through the spinnaker. The twist in the line will be minimized to nill."
I can't even tie my shoe laces! Do you know of anyone who provides this as a service?
You like to tinker, so I know you can do this Pete. If you know how to taper a main sheet, you can do it.
Mike