Ok, that was a strong ball 15 years ago, super low RG (2.44 or thereabouts), but its coverstock is one the weaker side of medium today.
Few balls today use such a low RG and the coverstocks are generally much stronger. The Ebonite Cyclone uses a similar coverstock but on a much high RG core and the cover is highly polished. You might be better off using modern ball that blends a better balance of medium RG core with a stronger coverstock. You might want to check videos of balls in the Ebonite family (Columbia, Hammer, etc.) that handle medium oil, like the TakeDown, Smackdown, Eruption series, Arson, Absolute Hook, and Ebonite's own Persevere.
There are also some new bal lines like Seismic that has the Euphoric,
http://www.bowlerx.com/Seismic-Euphoric-Bowling-Ball-SEISEUPHORIC.htmthat may be suitable.
There are a couple of balls with a super low RG but my initial reaction is that these will be stronger than the Vortex II on today's oil. One such is the Storm IQ Tour solid:
http://www.bowlerx.com/Storm-IQ-Tour-Bowling-Ball-STIQTOUR.htmKeep in mind one very important factor here. Your Vortex is very, VERY old by bowling standards. I have no idea how well you have kept it, how much oil it has absorbed over time, and what surface is on it now. They all have huge POTENTIAL effects on your balls current performance which is a total unknown. I have been speaking above, as if your Vortex were brand new. It obviously is not, but in what condition it is in is very variable.
