Th K-Jetronic system used up until 1988 on the 8v cars, as well as right to the end on the 16v cars, runs at significantly higher pressure than the Digifant system.
Whatever option you go for, make sure the replacement pump system will work and is suited.
I learnt this lesson on my South African VW Caravelle, which also uses Bosch K-Jetronic system, when i needed to source a suitable replacement pump back in 2011.