Here’s a photo from 1978 showing Greg recording the guitar tracks for the Nervous Breakdown EP. If you examine his guitar closely, you'll see it has a Flying V-style headstock, a light body and a black pickguard. I suspect it’s an Ibanez Rocket Roll, as Chuck Dukowski owned an Ibanez Rocket Roll bass around the same period.

Esta guitarra la usó con Serú Girán, la conocida "guitarra flecha". Fue usada para presentaciones en vivo hasta que la regaló en los 90 y luego fue robada.

Sylvain Sylvain in 1973 at a live perfomance / "New York Dolls Plays Ibanez" advert with his Ibanez Rocket Roll Sr.

Jerry can be seen in several pictures on Cirith Ungol's official website, Facebook page and a 1984 performance available on YouTube playing what looks like a Gibson Korina Flying V. However, this picture's angle allows to see better the headstock with the old Ibanez logo. This model was produced by Ibanez from about 1973 to 1978, thereby matching with the era when Jerry started playing in Cirith Ungol.

In the article "Bruce Franklin of Trouble: The ClassicRockHistory.com Interview" by Andrew Daly on ClassicRockHistory.com, it is confirmed that for the first 20 years in the band Trouble, he used a '76 Ibanez Rocket Roll (Flying V) electric guitar:

What guitars, gear, pedals, amps, and effects are you using, and why? How has that changed from your ’80s and ’90s heyday?

For the first 20 years of Trouble, I played a ’76 Ibanez Rocket Roll (Flying V) and used a ’79 Marshall JMP 100-watt amp. I still own both of those, but the DiMarzio pickup in the Ibanez died, and subsequent pickups don’t sound the same. The Marshall JMP had to be retubed and doesn’t sound quite the same, either.