Comments.....having run a single bypass filter on my full pressure 235 engine using the 1/8 NPT lines with no restrictor, I noted a 5-7 psi pressure drop. To me, this drop in pressure, coupled with the fact that the by-pass system only filtered 10% (max) of the oil and dumped the filtered oil back into the unfiltered oil, negated any benefit from the filter setup. I would surmize that using a double filter setup would reduce additional oil pressure. Changing the oil more frequently was a simple trade-off to replacing oil starved bearings.
I may be mistaken, but I doubt that a 1945 Canadian Military Pattern truck is going to accumulate so many miles that economically, it would warrant using a dual filter system. When you look at the initial cost of adding a dual filter setup with fittings and lines and the cost of changing both filters, I think you would be easier on your engine and your wallet to bump up the frequency of your oil changes.
Dave
