Wow, an extreme skid/flip ball! Ain't many like that any more. The SP would be a medium-light oil ball these days, unless he used it with a worn out track. If he re-surfaced it yearly, he probably also has it polished like new. Taking that into account ...
The Track closest in ball reaction might be the Xception, with a heavy coat of Magic Shine and a high pin placement, but that is a premium priced ball that you said he does not want.
I'd suspect a Visionary pearl, like the AMB Bronze Centaur might in the same neighborhood.
The Dyno-Thane Vendetta Pearl is an old fashioned skid/flip ball that might come close. It doesn't have that high differential but the pearlized coverstock might make up for it.
Brunswick's Punisher also has a similar look.
The Roto-Grip RS-1 also falls into this category.
Unfortunately most of the new coverstocks are a lot stronger than the Synergy's; that also means you don't need as high a differential to get a similar ball reaction.
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Bowling: Just like hand grenades and horse shoes, you only have to get close.
Life: Deal with what is.