I wouldn't say it's severe but it is annoying especially now I have my shifts timed right. Restrictor orifice seems like a good approach where can I get one and what size(s)do I need?
You stated that the front servo piston already had blocker installed (part of a shift kit) so the trans might also have a restrictor orifice installed. Before tearing into it try backing the band adjustment off to 2 or 2 1/4 turns.
As stated earlier, overlap is more pronounced at low speed low throttle so, if there is no noticeable overlap at WOT, you might be better off just living with it at low speeds.
The fancy billet servo pictured above would likely exacerbate overlap woes.
