Are there any mods?
If I understand correctly the JFET is distorting when you play harder...
Stick a pot on the input and reduce what you're feeding the tremolo, then you'll have/need/want/use the JFET to restore unity-volume and it won't distort as much.
You could also try reducing the JFET's gain by increasing R3 and decreasing R4, one or the other or a bit of both.
Go hog wild and try and make the JFET a BJT as per the original circuit, ie the Vox Repeat Percussion. I don't know if you'll get any less gain, though.
Since engaging a Tremolo often results in a perceived volume drop, I don't see why you'd want to remove the JFET from the circuit entirely. The circuit needs some kind of make-up gain, is it not something that should not/could not be removed?
The mod I'd do is add another on-off-on to SW-1's C7 or C8 and mess with some extreme values ala Moosapotamus' Skippy — 47uF! Then change out the B100k rate pot for C100k. Add another input cap on a pot for a rudimentary tone control... replace the 1uF with 47n and have the pot blend in a 2u2.
Have fun with it!