Indeed Pat is referring to the GR-300. I still have a GR-300 that I use with an Ibanez img2010 & Roland GR202 (plus sustainiac stealth pro)
Pat's guitar synth solo on Offramp's "Are you going with me" is stellar. https://www.youtube.com/watch?v=N6I02UdoT6w
The author of that premier guitar article has a wealth of info on his site regarding Roland synth guitars.
I've also purchased one of his 24pin to 13pin convertors - works perfectly... with all the inherit delays of guitar to midi.
I used a Roland G707 with GR-700 in the late 80's and really hated the delay... love the access to synth type sounds but that delay was remarkable. This lead me to getting the GR300... though as a guitar synth it's a one trick pony... it's a hell of a trick.
I have a Roland GR500 and GS500 as well and these track as well as the GR300, the CV out on these can be used to access older synths with CV input... a ton of new modular (and old) gear as well as the new crop of synths showing up with CV included