been there, done that
Yep, that one sounds all too familiar Andrew.
My '87 would just shut right the heck off out of nowhere with no symptom, indication, etc. And it would then start RIGHT back up by turning the key off / on. Spooky.
Replaced the fuel pump relay (large black regtangular multi-pronged unit located behind easily removable panel in back of battery box, it's one of the 2 there I think) for $160 or so, took all of about 23 seconds, and voila! It hasn't happened in the 8 months since. But mine would re-start no prob and stay running. I'd start there regardless.
NOTE* I'm told (Hendy) that there are 2 relays you can choose, the US and the Euro one. Be sure to go w/ the Euro, it provides the 7000 or 7200 (?) rpm redline that matches your motor, not the stupid 6800 (or so?) US one. I didn't know this until recently and would have opted for the Euro. Let us know how you fare, good luck, drive fast!