Quick Shift:

I made a quickshift my self with a bit of steel plate,two M6 Bolts and
Nuts and some washers.

Remove the selector arm from the gearbox, by undoing the 13mm nut and
hitting it off the spline.
(make sure you make a note of the position when it is removed)
The unclip and unhook the link rod at both ends, so it can be removed from
the car along with the selector arm.

First you drill a 6mm clearance hole in the original selector arm, just
under the original hole with the nylon bush in.  (see diagram)  (A)
Then drill two 6mm clearance holes in a 2x1x1/4" steel plate the same
distance apart as the two holes in the selector.    (see diagram)   (B)
Then a third hole about an inch lower the same size as the original hole
in the selector arm  (see diagram)  (C)
Bolt the plate onto the selector arm with two 6mm bolts with large washers
both sides and locking nuts   (see diagram)
Put the nylon bush in the new hole and re-fit the arm to the gearbox and
re-connect the rod to it.

Quickshift is now in place, by reducing the throw of the arm.

A weighted rod to go with this can also be done easily.
I did mine by going to a metal fabricators on an industrial estate, asked
if they had a bit of steel bar about 1" diameter and 4" long, which they
gave me for nothing.
I then got two jubilee clips and clamped it to the original link rod,
weighted rod!!!

All this works perfectly, and cost a few pence, rather than the £50+ that
some places were asking for, and by varying the length of the steel plate
and the position of the new link rod hole it is possible to adjust the
reduction in throw.