So i owned a penhold PG7 once. it's a pretty good blade. Really affordable.
I prefer my Stinga Clipper but that's a little stiff probably for him.
I'll tell you this. I'm eyeing these sexy new Gambler Fire Dragon penhold blades.
https://www.zeropong.com/products_new
They have carbon in them and are clearly trying to emulate some of Butterfly's popular ZLC blades.. They even say so in the description.
But i'd go for either of their two thinner 5.8 I think thickness blades for looping. They have a thicker blade 6.something I think (kinda like my clipper) for more drive, power play.
But to your original post. Yes penhold wings that don't have the sanded wings are the worse. Sand those babies down. I use a dimmel. The end result should look like a completely beveled rounded corner on both sides top & bottom.
Another tip. I would do this if i was starting form scratch but alast I've been playing this way too long. Teach him to use the RPB 95% of the time. Sure in the cross over point or sometimes with sidespin chop-blocks a la Ma lin the TPB is better but other than that? RPB.
I have tried & tried to use the RPB more but instinctively on blocks i just use TPB.
Good luck.
I'm a lefty also who plays penhold. Have him watch the He Zhi Wen setup type of point with the side spinning pendulum serve breaking wide far off the table. If he can block the opponent's loop down the line, point is over 75% of the time. A good setup to emulate. He doesn't have to play short pips like He Zhi Wen to do this. Can be done with inverted all the same.