Bill Alston
The 300 Models
The SE 300 was one of the guitars launched in the 1985 catalogue and is featured on the first models English pages.
This page will detail the rest of the 300s, which are the SE 312, 312M, 350 and 350H. As far as I can ascertain all models
are made in Taiwan
The 312 and 312 M
The 312 and the 312M are the same model the M just indicates a Maple fretboard.

A Candy Apple Red 312 with a very interesting case
This extract from the catalogue shows some specs and colours available, it may be that black was also available but I can't be sure.

Additional details are this is 648mm scale 22 fret neck, the pickups are ferrite (ceramic), SSH controls 1 volume 1 tone with a coil split.
It is a wide radius fretboard and the total weight is 3.2kgs. The finish is matt. The 312 was launched in 1987 the M a year later.
Update 22 June 2017
I now have a different English Language 1988 catalogue which shows black is definitely available. The 312 has a Buvinga Fretboard and all
models have a 350mm radius.
The 350
The 350 and the 350H are the same model
but SSH and HH respectively.

The Sea green 350 is another one from Jeff Plogger's collection shown
next to a Candy Apple Red 350H
Update June 2017
I now have the launch brochure for the 350 the 350H also includes the 250 and the 150 so correct details below
The 350 and the 350H were launched in 1989 .
Some specs:
Neck Nato with a Bubinga Fretboard 648MM scale 22 frets
250mm radius 41mm nut
Body Campnosperma
Vibrato Rockin Magic 11 with locking nut
Pickups Ferrite SSH on the 350 HH on the 350H
Colours Sea Green, Pearl White, or Black plus Candy Apple Red on the 350H
Weight 3.7kgs
Controls 1 volume 1 tone and coil tap.