There needs to be a restrictor somewhere in the line of about 1/8" or so. Most bypass filters have one built in. Some don't. I used 3/16" Cu/Ni brake line. Has worked well for 4000 miles. Oil pressure remains in 235 specs.
Since the flow is restricted to 1/8, then 3/16" is all that is necessary for a bypass system.
If I were to use rubber lines, I would go with the proper length of high pressure grease-gun hose. That would mimic the OEM hoses of the day.
