As im planning on doing a turbo jobby to mine.. i opted to try the Mk1/2 Mondeo Auto Radiator with 2x oil cooler built in.
(part no: 93bb 8005 hc/he)
These im lead to believe and happy to be corrected were also used in the Rally spec pumas....
*Some Vauxhalls surprisingly reach '110-115deg C' before fan kicks in...
But saying this, i agree the stock radiator is indeed up for the task. Perhaps mate it with a different style of fan.
((Oddly enough my last puma 1.7 drove from Rochester to London, reaching the not allowed full sweep on the speedo, with less than min in coolant tank and intermittant working fan... never over heated once, even in traffic))