I took a close look in terms of available room for a bypass on the earlier cars with the 3X reservoir. There looks to be room to do it two different ways. Both routings are between the tanks and the belts/engine, one is just higher than the other to go either above or below an existing/parallel hose.
First routing in plan view while standing in front of the engine...
Second view is a cut and the plumbing is at a lower elevation that the above...
I looked at pex fittings as well but don't like the multiple ribbing where the clamp compresses the rubber. I agree with you Justin with respect to flow however.
I'll post more when I can.
Thanks for those mock ups Tobin, I prefer the first set up.
For now I have purged the system and reduced the amount of coolant an upped the water amount in the ratio, I will have the car out tomorrow and will report.
Thanks to all who have chimed in.