I've rebuilt a couple of these 235's and never encountered a "restrictor", unless it would maybe be the head bolt that the oil has to go by to get to the rockers.
But all is well. I hooked up an oil gauge today and had it maintain 45 PSI at a low idle, warmed up good.
If you have more on the restrictor please let me know. You aren't by chance thinking of the by-pass valve in the oil pump, are you?
