Great to see all the Naylor love!
Fantastic, unique amp that I've gone back to several times. I'm looking at you, silver sparkle D100.
A buddy just picked up a SD38 and likes it even better than his 60. Makes me want to check one out.
I'm going to go against the popular vote, and suggest something else.
You say you have
Marshall and Recto-ish covered. To me, a Naylor is like a perfect compromise between those two amps, with a dash of Bogner/Friedman/Wizard flavor thrown in. In fact, you might find a Naylor would make the DC3 and JJ Jr obsolete. It'll do those sounds, and a whole lot more, with better lead tones than either. Imo, of course.
Naylor is smoother on the top end and more compressed than a Wizard Modern Classic or some of the VHT/Fryette amps, both of which can be off-putting to some folks. They are very open, raw and direct feeling.
I think you'd be well served with a Mesa Mark style amp, or one of the earlier Caliber amps that are Mark-like on the cheap. They're slightly more forgiving on attack than the Wizard or VHT, while still providing the raw, chainsaw like grind you describe.
Here's a thrashy clip I made of the Wizard MC I had:
And one of a Mesa .50 Caliber Plus I have now
I'd pick either of these amps over a Naylor for thrash metal type stuff. I'd take a Naylor for anything else, up to 90s hard rock like AIC, Tool. It's better for AIC than the JJ Jr, imo.
Here's how heavy a Naylor gets:
It's up there with SLO as one of my fav amps for solos. Naylor is a special amp.