1) Early 50's "Powerglide" 235 and later car engines were full-flow high pressure engines but never had full-flow remote oil filtration. That was for 261 only.
2) Correct, factory made the filter unit optional because of fleet requirements. There is a dowel in the block that must be punched in to block the filter in & out connections, forcing oil out to the filter. If frozen in place, it can be risky trying to move this dowel.
3) Beehive filter just replaces the cannister - line size is too small for the big 261 lines.
The best way to be certain on the filter lines is to pull the pan and follow the oil pump path to the main oil galley. This path will be under oil pressure and will have a threaded hole for a pipe fitting out to the filter. Check the 2 lower holes and at least one should go all the way through the block into the crank case. This is the return path. Use the most convenient one and plug the other. Or (my preference) plug all holes, forget the bypass filter and change your oil frequently.
