best bet is to find another 8v rad and fit a leci fan to it as a back up system
pug fans are thin something off a 205 or such
you can either have it wired to a switch on the dash so when it gets hot you can manually switch it on or there is a kit on ebay for about £30 that you plumb into the water system and it has a thermostate switch so it comes on at a certain temp set by the user
hope this helps
simon
ps you cud also as a temp fix during summer months take out the engines thermostate