3 point rear seal belt / racing harness?

Hi all. I need to get my kids into the back of my 87 cabrio.i read somewhere about fitting a racing harness. Can anyone shed any light on this matter please?

Get yourself over to crazy quiffs for rear belt conversion. Kit is based on volkswagens U.S spec mk1s. Still to fit mine but the kit looks great and includes belts.

Need some help please. 1987 Mark 1 golf . After about 20 minutes of driving car loses power. Its like someone is pumping the accelerator up and down. The car will eventually stop. Let it sit for a min and then off I go again. Also,  if I accelerate hard past 5000 rpm ( don't do that very often) car will miss and lose power. Not sure if both symptoms are linked.  Leads have been replaced,  new alternator too. Any ideas please?

CIS or Carbed?