[quote]The fact that you got signed off without even holding a PPASEL is the first clue in figuring this out...

If you have a logbook with the endorsement signed by an instructor, it is good "for life",regardless of anything. That endorsement is the same one given to a PP-holder getting a tailwheel "add-on", as I did. There's no time limit on it, nor is there any flight review requirement specifically for operation of "conventional gear" aircraft.
But that endorsement also does not override any currency requirements relative to your PPASEL (the 90-day rule for carrying pax, BFRs, etc.), nor will it allow you to be turned loose (given the interval simce you last flew a taildragger) without some review in a taildragger that does not belong to you, unless the owner is very naive or very stupid.