There are countless motors I’ve tested where I’ve forgotten I even tested them, much less the details about what was done on the dyno, but I can’t think of a single instance where I picked that kind of power by “tuning”.
Usually, when they’re down on power that much, something needs replacing.

I can think of a time or two where there was 30hp or so found in messing with the carb........but that was something that was totally out to lunch to begin with.

Unless you have something pretty far off from what the motor wants, I’d say if you picked up an honest 15hp, you’d be doing okay.

But, that’s why you test......... you might have something that’s way off.

Buy yourself a non-dial back timing light.